Granular Absorbent and System and Method for Treating or Processing Granular Absorbent During Granular Absorbent Transport

ABSTRACT

A system and method for treating or processing granular absorbent while the granular absorbent is being transported in a fluid stream that preferably is a stream of air. The system includes a pneumatic conveyor with a conduit that draws pellets exiting an extruder into the conduit drying the pellets as they are transported through the conduit. Material can be introduced that dries, coats or otherwise treats the pellets while the pellets are transported through the conduit. Coating material, e.g., powdered bentonite can coat and also dry pellets during transport. A conduit can have inner pellet treating surface that abrades pellets transported through the conduit producing smaller fines that can be packaged with pellets forming a granular absorbent product that forms clumps on top that extend generally horizontally.

CROSS REFERENCE

This application claims priority in U.S. Provisional Patent ApplicationNos. 61/931,609 filed Jan. 25, 2014 and 61/952,133 filed Mar. 12, 2014under 35 U.S.C. §119(e), and is a continuation-in-part of each of U.S.patent application Ser. No. 13/868,084 filed Apr. 22, 2013, U.S. patentapplication Ser. No. 13/868,073 filed Apr. 22, 2013, and U.S. patentapplication Ser. No. 13/842,534 filed Mar. 15, 2013, each of whichclaims priority in U.S. Provisional Patent Application No. 61/775,707filed Mar. 11, 2013 and in U.S. Provisional Patent Application No.61/699,858 filed Sep. 11, 2012 under 35 U.S.C. §119(e) the entiredisclosure of each of which is expressly incorporated herein byreference.

FIELD

The present invention is directed to granular absorbent, includingself-clumping granular absorbent, and more particularly to a system andmethod for treating or processing granular absorbent during granularabsorbent transport.

BACKGROUND

While attempts have been made in the past to produce a lighter, morenatural, and even biodegradable cat litter, improvements nonethelessremain desirable. Conventional clay-based and gel-based litters arerelatively heavy, cost a considerable amount of money to ship, and areoften a burden for purchasers to carry. While many so-called natural catlitters have been introduced into the marketplace, they can be nearly asheavy as conventional litter, typically absorb far less urine thanconventional litter, can produce their own unpleasant odor, and manytimes do not clump well, if they even clump at all.

SUMMARY

The present invention is directed to a system and method for processinggranular absorbent during transport that includes a pneumatic conveyorthat provides granular absorbent transport while (a) drying granularabsorbent, (b) cooling granular absorbent, (c) performing granularabsorbent surface preparation, (d) coating granular absorbent, (e)wetting granular absorbent, and/or (f) liquid treating granularabsorbent is carried out. In one preferred system and method ofprocessing granular absorbent during transport of the granularabsorbent, at least a plurality of (a) drying, (b) cooling, (c)performing surface preparation, (d) coating, (e) wetting, and (f)treating of granular absorbent are performed during transport. Inanother preferred system and method, a plurality of pairs, i.e., atleast three, of (a) drying, (b) cooling, (c) surface preparation; (d)coating, (e) wetting, and (f) treating granular absorbent are performedduring granular absorbent transport.

In a preferred system embodiment, the pneumatic conveyor has a conduitthat preferably is an elongate duct with an intake at one end throughwhich granular absorbent enters where the granular absorbent istransported through the duct to a duct outlet at the opposite end wherethe granular absorbent is discharged. Where the pneumatic conveyor isused to transport granular absorbent from an extruder, the intake of thepneumatic conveyor duct is disposed adjacent a discharge end of theextruder and configured to enable extruded granular absorbent to enterthe intake within a second or two of being extruded. Where the pneumaticconveyor is used to transport granular absorbent from an extruder,processing of granular absorbent can be performed immediately uponextrusion during transport into the pneumatic conveyor duct inlet and/orduring transport of the extruded granular absorbent through thepneumatic duct.

In one preferred system and method in accordance with the presentinvention, the granular absorbent is an extruded granular absorbent thatis extruded by a single screw or twin screw extruder. The extrudedgranular absorbent is then transported by the pneumatic conveyor awayfrom the extruder. Processing of the extruded granular absorbent ispreferably performed after extrusion including while the extrudedgranular absorbent is being transported. In one such preferred systemand method used to process extruded granular absorbent during transport,extruded granular absorbent is transported by the pneumatic conveyorwithin a second or two of being extruded by the extruder. In the samepreferred system and method, processing of the extruded granularabsorbent would be performed during transport by the pneumatic conveyor.In another such system and method, processing of the extruded granularabsorbent occurs right after extrusion and during pneumatic conveyortransport.

A preferred extruded granular absorbent is extruded in the form ofliquid-absorbent pellets composed of starch-based or starch-containingmaterial and/or fiber that preferably includes insoluble fiber, e.g.,cellulose. The liquid-absorbent pellets preferably include a binder inan amount sufficient in each pellet to cause pellets to readily clumptogether when wetted by a liquid, such as water, urine, liquid fecalmatter, or another waste or toxic liquid, thereby producingself-clumping liquid-absorbent pellets. Such a binder can be, but is notlimited to, a starch-based or starch-containing bioadhesive such asdextrin, and/or a synthetic adhesive, such as an acrylic adhesive, whichis carried by, e.g., coated, and/or disposed in each pellet in an amountsufficient to produce self-clumping liquid-absorbent pellets. Such abinder can be extruded in each pellet during granular absorbentextrusion and/or applied to the pellets after extrusion.

A preferred granular absorbent is formed of liquid-absorbent pelletshaving a binder in a sufficient amount to produce clumps when wetted byliquid, namely water, urine or another waste liquid, formed of at leasta plurality of pairs, i.e., at least three, of pellets in each clumpthat each possess at least 90% clump retention and/or which have a crushor compressive strength of at least 25 pounds per square inch (PSI) andpreferably at least 40 PSI when the clump is substantially dry (havingbetween 10% and 15% moisture by clump weight). One such preferredgranular absorbent is formed of liquid-absorbent pellets having a binderin a sufficient amount to produce clumps when wetted during use as aliquid absorbent that possess at least about 90% clump retention (±3%)and which have a crush or compressive strength of at least about 50 PSI(±5%) when the clump is substantially dry.

One such preferred granular absorbent is formed of liquid-absorbentpellets each having binder sufficient to self-clump when wetted by wateror urine producing clumps possessing at least 95% clump retention and/orhaving a crush or compressive strength of at least 25 PSI and preferablyat least 40 PSI when the clump is substantially dry. Another suchpreferred granular absorbent formed of liquid-absorbentbinder-containing pellets produces clumps when wetted that possess atleast about 95% clump retention (±3%) and that have a crush orcompressive strength of at least about 50 PSI (±5%) when the clump issubstantially dry.

Another preferred granular absorbent is formed of liquid-absorbentpellets having at least 15% water-soluble binder, by uncoated pelletweight, in the form of a starch-based or starch-containing water solublebinder, which can be cold water soluble and/or include or contain atleast some dextrin, which is an amount of water soluble bindersufficient to produce self-clumping of wetted pellets during liquidabsorbent use producing clumps formed of at least a plurality of pairs,i.e., at least three, of the pellets that each at least about 97% clumpretention (±3%) when the clump is substantially dry (having between 10%and 15% moisture by clump weight). One such preferred granular absorbentis formed of liquid-absorbent pellets having at least 18% water-solublebinder, by uncoated pellet weight, in the form of a starch-based orstarch-containing water soluble binder, which can be cold water solubleand/or include or contain at least some dextrin, which is an amount ofwater soluble binder sufficient to clumps possessing at least 95% clumpretention and having a crush or compressive strength of at least 50 PSIwhen the clump is substantially dry. Another such preferred granularabsorbent is formed of liquid-absorbent pellets having at least 20%water-soluble binder, by uncoated pellet weight, in the form of astarch-based or starch-containing water soluble binder, which can becold water soluble and/or include or contain at least some dextrin,which is an amount of water soluble binder sufficient to clumpspossessing at least 95% clump retention and having a crush orcompressive strength of at least 50 PSI when the clump is substantiallydry. A further such preferred granular absorbent is formed ofliquid-absorbent pellets having at least 25% water-soluble binder, byuncoated pellet weight, in the form of a starch-based orstarch-containing water soluble binder, which can be cold water solubleand/or include or contain at least some dextrin, which is an amount ofwater soluble binder sufficient to clumps possessing at least 95% clumpretention and having a crush or compressive strength of at least 50 PSIwhen the clump is substantially dry. Still another such preferredgranular absorbent is formed of liquid-absorbent pellets having at least30% water-soluble binder, by uncoated pellet weight, in the form of astarch-based or starch-containing water soluble binder, which can becold water soluble and/or include or contain at least some dextrin,which is an amount of water soluble binder sufficient to clumpspossessing at least 95% clump retention and having a crush orcompressive strength of at least 50 PSI when the clump is substantiallydry.

Such high clump retention granular absorbent produces clumps thatadvantageously retain more of the liquid absorbed by the clumped pelletswith the clump by retaining substantially all of the clumped pelletswith the clump because very few pellets fall off the clump duringremoval. Such clumps also better retain their integrity when bumped,walked on, displaced or otherwise contacted or moved, further helping toensure that a maximum amount of absorbed liquid is removed with theclump when the clump is removed and disposed of.

Such high crush or compressive strength granular absorbent is formed ofliquid-absorbent pellets that readily self-clump when absorbingwaste-containing liquid, such as urine or liquid fecal matter, but allowwater in the waste-containing liquid to evaporate during drying of theclump while capturing and retaining toxic or waste component(s) presentin the waste liquid when absorbed to form the clump. When dried, such ahigh crush or compressive strength clump advantageously encapsulates orlocks toxic or waste component(s) within the clump preventing toxic orwaste component(s) from evaporating during drying or even solubilizingshould the clump be re-wetted.

In a preferred system and method of processing granular absorbent duringtransport, pellets of granular absorbent are transported in air flowingin a conduit of the pneumatic conveyor, preferably an elongate tubularduct, during which one or more processing steps are performed on thepellets. The pneumatic conveyor includes an air mover, such as in theform of a blower, fan, compressor, or pump, which causes air to flowthrough the duct in a manner that draws pellets of granular absorbentinto a duct intake at one end of the duct and transport the pelletstoward a duct outlet at the opposite end of the duct. Such an air movercan be configured to push air through the duct or can be configured tosuck air through the duct.

Where such a system is used to process extruded granular absorbent incarrying out a method in accordance with the invention, pellets ofuncoated granular absorbent are transported through the duct by thepneumatic conveyor within a second or two after being extruded from theextruder in a granular absorbent transport step during which at leastone processing step and preferably at least a plurality of processingsteps are performed on the pellets. In such a system, the intake of theduct is located adjacent a discharge of the extruder enabling at least aplurality of pairs, i.e., at least three, of liquid-absorbent pelletsextruded per second of extruder operation to be transported into theduct intake within a second or two of being extruded.

A preferred system for processing extruded granular absorbent duringpneumatic conveyor transport can include an extruder discharge chamberdisposed at the discharge end of the extruder to which the pneumaticconveyor duct is connected enabling pellets of granular absorbentextruded by an extruder to enter the duct intake within a second or twoof being extruded by the extruder. The discharge chamber can be ofsubstantially gas-tight construction and can be substantiallygas-tightly sealed to the extruder. If desired, the discharge chambercan include one or more vents that can be selectively opened or closedduring operation to help regulate the flow of air through the system.

Where the system includes such a discharge chamber, the chamberpreferably is an enclosure that substantially completely encloses thedischarge end of the extruder, positioning the duct intake close enoughto a discharge, e.g., perforate extruder die plate, of the extruder toreceive pellets as they are extruded. Air flow through the pneumaticconveyor duct transports the extruded pellets through the dischargechamber into the duct intake where the pellets are further transportedthrough the duct toward the duct outlet.

If desired, the system can include one or more nozzles that eachdischarge at least one stream of gas, preferably air, generally towardthe discharge end of the extruder to help prevent extruded pellets ofgranular absorbent from sticking or otherwise accumulating outside thepneumatic conveyor duct intake helping to maximize the amount ofextruded pellets transported by the pneumatic conveyor. Where one ormore such gas nozzles are used, they can be used in a system lacking anyextruder discharge chamber as well as in a system employing an extruderdischarge chamber. Where used in a system with an extruder dischargechamber, one or more such gas nozzles can be carried by or otherwisemounted to the chamber. Where one or more such gas nozzles are used,they preferably are provided in the form of one or more air-knives eachhaving an elongate or slot-shaped nozzle from which a stream of air,e.g., pressurized air, is expelled.

In a first preferred implementation of a method in accordance with thepresent invention, a granular absorbent drying step is performed whilethe granular absorbent transport step is carried out such that extrudedliquid-absorbent pellets of granular absorbent are dried duringtransport of pellets away from the extruder. During the drying step, themoisture content of the extruded liquid-absorbent pellets is reducedduring transport of the pellets away from the extruder during thetransport step. To dry extruded liquid-absorbent pellets duringtransport, sufficient air at a great enough volumetric flow rate havinga high enough temperature and a low enough humidity is moved by the airmover through the pneumatic conveyor duct or conduit to causeevaporative moisture transfer from the pellets to the flowing airreducing pellet moisture content. Air preferably is drawn from ambientoutside the extruder and conduit by the pneumatic conveyor with theambient air preferably having a temperature no greater than 32 degreesCelsius and preferably having a temperature of about room temperature,e.g., between 20-24 degrees Celsius. Air flowing through the conduitduring cooling and drying of the granules or pellets carried by the airpreferably has a temperature no greater than 50 degrees Celsius andpreferably less than 45 degrees Celsius at or adjacent, e.g., downstreamof the inlet or intake of the conduit.

In one drying method step implementation, the drying step is performedas the extruded liquid-absorbent pellets are being transported duringthe transport step through at least a portion of the duct of thepneumatic conveyor reducing a moisture content of the pellets duringtransport. In one such drying step implementation, the drying stepbegins being performed immediately upon extrusion of the pellets fromthe extruder during transport of the pellets away from the extruder intothe duct intake during the transport step. The drying step can continuebeing performed while the pellets are being further transferred throughat least a portion of the duct downstream of the intake during thetransport step.

In carrying out such a drying method step implementation where thedrying step begins being performed upon pellet extrusion, an initialmoisture content of the pellets upon extrusion is reduced to a finalmoisture content that is less than the initial moisture content when thedrying step is completed in the pneumatic conveyor duct. Where thedrying step is performed during the entire transport step, the pelletmoisture content is reduced from initial moisture content upon pelletextrusion to final moisture content upon pellet discharge from thepneumatic conveyor duct that is less than the initial moisture content.

In carrying out a preferred drying method step implementation, the ductof the pneumatic conveyor of a preferred system embodiment is sized toenable an air flow rate through the conduit of between 500 CFM and 3000CFM and preferably between about 1500 CFM and 2750 CFM, and an air speedgreat enough to produce turbulent air flow through the duct to moreefficiently and/or more quickly dry the liquid-absorbent pellets ofgranular absorbent entrained in the turbulently flowing air flowingthrough the duct during transport. In one system embodiment and dryingmethod step implementation, the duct has a size and/or cross-sectionalarea through which air at such a flow rate and/or velocity flows thatproduces turbulent air flow through the duct that reduces pelletmoisture content by at least 1% during the drying step. In anothersystem embodiment and drying method step implementation, the duct has asize and/or cross-sectional area through which air at such a flow rateand/or velocity flows that produces turbulent air flow through the ductthat reduces pellet moisture content by at least 2% during the dryingstep. In still another system embodiment and drying method stepimplementation, the duct has a size and/or cross-sectional area throughwhich air at such a flow rate and/or velocity flows that producesturbulent air flow through the duct that reduces pellet moisture contentby at least 3% during the drying step.

Drying of liquid-absorbent pellets in such a drying step carried outduring the transport step advantageously reduces the amount of shrinkageof the pellets that ordinarily takes place after extrusion therebyhelping to keep pellet density lower than if drying was not performedduring pellet transport. Where the pellets are expanded or puffedpellets extruded under superheated and/or adiabatic extruder operatingconditions, starting the drying step immediately after extrusion duringpellet transport away from the extruder advantageously optimizes pelletdensity by minimizing shrinkage thereby producing liquid-absorbentpellets having a desirably low density that are well suited for use in awide variety of consumer and commercial liquid absorbent applications.

Where the drying step is performed during transport of uncoatedliquid-absorbent pellets to facilitate coating of the pellets, dryingpreferably is carried out as quickly as possible after pellet extrusionto help minimize post-extrusion pellet shrinkage or densificationthereby helping to keep pellet density optimally low. Where coated, thepellets preferably form lightweight cores substantially completelycovered by coating material. Such lightweight cores formed by suchpellets intended to be coated preferably are void-filled and/or porous,having a desirably low density or density range prior to coating inaccordance with that disclosed elsewhere herein. In one such preferredmethod implementation where uncoated puffed or expanded pellets areextruded under superheated or adiabatic extrusion conditions, moisturewithin pellets being extruded flashes or vaporizes upon extrusionproducing hot moist pellets whose post-extrusion pellet density increaseis advantageously minimized by starting to perform the drying stepimmediately upon extrusion.

Carrying out such a preferred method implementation of pellet dryingduring transport that facilitates coating of uncoated liquid-absorbentpellets formulated for being coated advantageously produces lightweightlow-density liquid-absorbent pellets well suited for use as pet oranimal litter, e.g. cat litter, when coated that have an uncoateddensity of less than 12 pounds per cubic feet, preferably between 2 and10 pounds per cubic feet, which in turn produces relatively lightweightliquid-absorbent coated pellets having a density of less than 35 poundsper cubic feet, preferably between 20 and 45 pounds per cubic feet. Inone such preferred drying step method implementation where the pelletsare dried to facilitate coating, performing the drying step immediatelyupon extrusion of puffed or expanded liquid-absorbent pellets producesuncoated pellets having a desirably low density of between 3 and 8pounds per cubic feet which in turn produces coated liquid-absorbentpellets well suited for use as cat litter that possesses a desirably lowdensity of between 26 and 32 pounds per cubic feet. In another suchpreferred drying step method implementation where the pellets are driedto facilitate coating, performing the drying step immediately uponextrusion of puffed or expanded liquid-absorbent pellets producesuncoated pellets having a desirably low density of between 5 and 12pounds per cubic feet which in turn produces coated liquid-absorbentpellets well suited for use as cat litter that possesses a desirably lowdensity of between 25 and 30 pounds per cubic feet.

Where such low density relatively lightweight coated liquid-absorbentpellets produce a granular absorbent product for use as cat litter, apreferred pellet coating includes at least one smectite, preferably anabsorbent clay, e.g., sodium bentonite and/or calcium bentonite, whichhelps facilitate urine and liquid fecal matter absorption during litteruse. The pellet coating can further include one or more of a zeolite,sodium bicarbonate, sodium carbonate, sodium chloride, calciumbicarbonate, calcium carbonate, calcium chloride, silica, e.g.,crystalline silica, a binder, e.g. guar gum and/or an acrylic binder, ananti-bacterial agent, an anti-fungal agent, and/or an anti-parasiticagent.

Where the coating material includes a binder, it preferably is in adried granular, e.g., powdered, form that is easily mixed with the restof the coating material constituents disclosed herein. Where the coatingmaterial includes a binder, the binder can be a gum, such as guar gum,an acrylic, an acrylic-based binder, an acrylic-containing binder, astarch-based or starch-containing binder, a dextrin binder, adextrin-based or dextrin-containing binder, a bioadhesive, or anotherbinder that can be included, e.g., mixed with coating material that isapplied to granules or pellets during the coating step at leastpartially coating the granules or pellets with a coating materialcontaining binder that facilitates or enables self-clumping of aplurality of granules or pellets when wetted during absorbent use. Suchbinders preferably are mixed with the other coating materialconstituents in granular form, preferably dry granular form, and can bein powdered form, including where the coating material is provided in apowdered form, such as in accordance with that disclosed herein.

Keeping uncoated pellet density optimally low by preventing shrinkage bydrying the pellets as quickly as possible after extrusion help produce acoated pellet that also has a desirably low density prior to coatingthat produce coated pellets that are advantageously lightweight yetstill highly absorptive. Such low density coated pellets advantageouslyare well suited for use as cat litter, producing litter having a densityless than one-half that of conventional clay-based or bentonite litters.This means that a litter made of such low density coated pelletsadvantageously weighs less than one-half that of convention clay-basedor bentonite litters per a given volume.

Where the extruded liquid-absorbent pellets are formulated for liquidabsorbent use in an uncoated pellet form well suited for cat litter use,uncoated liquid-absorbent pellets are dried in a drying step performedduring pellet transport away from the extruder that advantageouslyminimizes pellet shrinkage helping to keep uncoated pellet densitybetween 20 pounds per cubic feet and 50 pounds per cubic feet. In onesuch preferred method implementation, the drying step is performedduring uncoated extruded pellet transport produces uncoatedliquid-absorbent pellets, including uncoated liquid-absorbent pelletsformed by superheated or adiabatic extrusion, which have an uncoatedpellet density of between 20 pounds per cubic feet and 35 pounds percubic feet that are also well suited for use as litter. One suchuncoated liquid-absorbent pellet well suited for use as litter has anuncoated pellet density of between 25 pounds per cubic feet and 32pounds per cubic feet after the drying step is performed duringtransport of the pellets away from the extruder as well as through atleast part of the pneumatic conveyor conduit during the transport step.

In a second preferred method implementation, a cooling step can beperformed while extruded liquid-absorbent pellets are transported duringthe transport step. In carrying out such a method implementation where acooling step is performed, pellet cooling can be performed in carryingout such a cooling step during pellet transport in the pneumaticconveyor duct through at least a portion of the duct extendingdownstream of the duct intake. In one second preferred methodimplementation, drying and cooling are performed during the transportstep with the cooling step preferably performed during at least part ofthe drying step.

Where a cooling step is performed during pellet transport, cooling ofthe extruded liquid-absorbent pellets can also help preventpost-extrusion pellet shrinkage or densification helping to keep pelletdensity desirably low in accordance with the maximum densities andpreferred density ranges discussed above. Where a cooling step isperformed during transport in a second method implementation where apellet drying step also is performed, the combination of pellet dryingand pellet cooling carried out during pellet transport canadvantageously work together, such as synergistically, to minimizepost-extrusion pellet shrinkage or densification helping to keep pelletdensity less than the maximum densities and preferably within thepreferred density ranges discussed above.

Where a cooling step is performed during pellet transport, each granuleor pellet preferably is cooled at least 10 degrees Celsius andpreferably at least 15 degrees Celsius during pellet transport. In apreferred cooling step, each granule or pellet preferably is cooled atleast 15 degrees Celsius to a temperature that is within 10 degreesCelsius of room temperature, e.g., within 10 degrees Celsius of 23degrees Celsius.

In a third preferred method implementation, a surface preparation stepis performed during transport of the liquid-absorbent pellets during thetransport step. Such a surface preparation step can be performed to helpincrease absorption and/or improve absorption characteristics of thepellets. Where the pellets are intended to be coated, performing such asurface preparation step helps prepare the pellets for being coated.Carrying out such a surface preparation step during pellet transporthelps prepare an outer surface of the pellets by removing projectionsand other surface discontinuities therefrom reducing pellet surfaceroughness.

A preferred surface preparation or surface treatment step abradespellets of granular absorbent being transported through the duct of thepneumatic conveyor via contact with other pellets and/or an interiorsurface of the duct during transport producing fines of granularabsorbent that are smaller in size than the pellets. Such an interiorsurface of the duct can be ribbed or otherwise three-dimensionallycontoured, e.g., roughened, to help abrade pellets during transportthrough the duct.

In a preferred surface treatment or preparation step, thepellet-abrading interior surface of the granule or pellet transportconduit of the pneumatic conveyor produces fines by breaking pieces offof the granular absorbent granules or pellets being transported throughthe pneumatic conveyor conduit that are smaller in size than each one ofthe granules or pellets being transported. In one preferred surfacetreatment or preparation step, uncoated granules or pellets are usedsuch that the fines produced are granular absorbent fines formed by thepellet abrading interior surface of the pneumatic conveyor conduitbreaking pieces of granular absorbent off of uncoated granules orpellets of granular absorbent pellets being transported through theconduit.

In one such preferred surface preparation method step implementation,the surface preparation step is performed during the transport steppreferably while at least one other processing step is carried outduring the transport step. In one surface preparation method stepimplementation, a drying step, such as a drying step in accordance withthat described herein, is carried out during a transport step where asurface preparation step also is carried out. In one such surfacepreparation method step implementation, the surface preparation step iscarried out during the drying step. In one such surface preparationmethod step implementation, the surface preparation step is carried outduring a transport step where both a drying step and a cooling step arealso carried out.

Removing projections and surface discontinuities from pellets duringsurface preparation produces pellets having a more uniform outer surfacethat coats more uniformly with coating material advantageously enablinga lesser amount of coating material to be used during pellet coating.Removing such projections and surface discontinuities from pelletsduring the surface preparation step also forms openings or pores in thepellets improving pellet absorption.

The projections and surface discontinuities removed from pellets duringthe surface preparation step produce fines of granular absorbent thatare smaller in size than the pellets. In a preferred surface preparationmethod step implementation, liquid-absorbent fines are produced thathave a size no greater than one-tenth average pellet size.

In a method of making a preferred granular absorbent product, the finesproduced during the surface preparation step are transported with thepellets during the transport step where the fines and pellets aretogether discharged out the outlet of the pneumatic conveyor duct. Finesremain with the pellets during any subsequent granular absorbentprocessing steps carried out after discharge from the pneumatic conveyorto produce a granular absorbent product packaged for retail, consumer orcommercial sale or use that is a mixture of liquid-absorbent fines andliquid-absorbent pellets.

In one preferred surface preparation method step implementation,carrying out the surface preparation step forms enough fines to producea preferred granular absorbent product that is a mixture of fines andpellets that contains at least 1% fines by packaged granular absorbentproduct weight. Whether coated or uncoated, granular absorbent productformed of such a first mixture of liquid-absorbent fines andliquid-absorbent pellets having at least 1% fines by packaged granularabsorbent product weight produces a granular absorbent product wellsuited for liquid absorbent use.

In another preferred surface preparation method step implementation,enough fines are formed to produce a liquid-absorbent granular absorbentproduct having at least 10% fines and preferably at least 15% bypackaged granular absorbent product weight. In still another preferredsurface preparation method step implementation, enough fines are formedto produce a liquid-absorbent granular absorbent product having between5% and 35% fines, preferably between 10% and 30%, and more preferablybetween 15% and 25% fines, by packaged granular absorbent productweight. Such preferred granular absorbent products are particularly wellsuited for use as cat litter because the mixture of liquid-absorbentfines and liquid-absorbent pellets clump together when wetted by water,urine and/or liquid fecal matter to form clumps of pellets and finesthat remain on top of a litter box filled with the granular absorbentproduct. In addition, the clumps of pellets and fines that form whenwetted advantageously have a clump width and/or clump length greaterthan clump depth enabling the clumps to be easily scooped from a litterbox filled with the granular absorbent product.

In a fourth preferred method implementation, a coating step is performedduring the transport step where liquid-absorbent pellets are at leastpartially coated with a coating material during transport. In onepreferred coating step method implementation, a coating step isperformed during a transport step where a drying step also is performed.In another preferred coating step method implementation, a coating stepis performed during a transport step where a surface preparation stepalso is performed. In still another preferred coating step methodimplementation, a coating step is performed during a transport stepwhere a drying step and a surface preparation step are also performed.In a further preferred coating step method implementation, a coatingstep is performed during a transport step where a drying step, a coolingstep, and a surface preparation step are also performed.

In a preferred coating method step implementation, carrying out thecoating step also dries and/or facilitates surface preparation such thatat least part of the coating step and drying and/or surface preparationsteps can be carried out substantially simultaneously during thetransport in such a method implementation. In one such coating methodstep implementation, carrying out the coating step helps dry theliquid-absorbent pellets during transport of the pellets during thetransport step.

In one preferred coating step, coating material is applied duringtransport of the pellets while the pellets still have a tacky or moistouter pellet surface after extrusion such that the tacky outer pelletsurface facilitates adhesion of the coating material onto each pelletwhile tacky. In such a preferred coating step, applying coating materialduring transport while the pellets are still tacky not only uses thestickiness of the tacky outer pellet surface to adhere the coating toeach pellet during transport, adherence of the coating material to thetacky outer surface of each pellet during transport also advantageouslydries each pellet. In another preferred coating step, pellets are wettedduring transport causing the pellets to become tacky enough for coatingmaterial to stick to or adhere to the tacky outer pellet surface duringpellet transport.

A preferred coating material is a granular coating material containingat least one smectite, such as absorbent clay, preferably bentonite,such as sodium bentonite and/or calcium bentonite. Such aliquid-absorbent pellet coating formulation is well suited for use in abroad range of granular absorbent product applications including catlitter. Where the coating material is intended for cat litter use, thegranular coating material can further include one or more of a zeolite,sodium bicarbonate, sodium carbonate, sodium chloride, calciumbicarbonate, calcium carbonate, calcium chloride, silica, e.g.,crystalline silica, an anti-bacterial agent, an anti-fungal agent,and/or an anti-parasitic agent, if desired.

In a preferred coating method step implementation, such a granularcoating material is applied to liquid-absorbent pellets immediately uponbeing extruded from an extruder during the transport step when theextruded pellets are being transported away from the extruder. Where theextruded pellets are puffed or expanded pellets, such as when extrudedduring superheated and/or adiabatic extrusion conditions, applyinggranular coating material onto the moist pellets within no more than asecond or two after being extruded helps facilitate adhering at leastsome coating material to the freshly extruded pellets.

Where the granular coating material is dry enough, application ofgranular coating material to moist pellets within no more than a secondor two after being extruded not only helps adhere at least some coatingmaterial to the freshly extruded pellets, the coating material alsohelps dry the freshly extruded pellets by absorbing at least some pelletmoisture. Helping to begin drying of the freshly extruded pellets withina second or two of being extruded advantageously helps minimize pelletshrinkage thereby advantageously helping to keep pellet densityoptimally low to produce a relatively lightweight low-density coatedgranular absorbent product.

Where the extruded pellets contain water-soluble binder, such as astarch-based or starch-containing binder, e.g., dextrin, binder presentin the moist outer surface of the freshly extruded pellets provides atacky outer pellet surface to which particles of granular coatingmaterial readily adhere to when beginning the coating step immediatelyafter extrusion. As particles of granular coating material adhere to thetacky outer pellet surface, the particles not only absorb pelletmoisture, at least some particles also bond and/or at least partiallyabsorb some of the binder present in the outer pellet surface. Duringpellet drying, including during application of granular coating materialduring the coating step, the binder can set causing adhered particles ofcoating material to become more tightly adhesively attached.

During such a coating step where particles of granular coating materialare applied to pellets while the pellets are moist or even wet, at leastone coating layer begins to form that at least partially coats pelletswith the coating layer composed of binder and coating materialparticles. This produces a coating that at least partially coats pelletsduring the coating step that is formed of at least one outerwater-soluble binder resin layer in which particles of coating materialare embedded, bonded and/or partially absorbed. As a result of being atleast partially coated with at least one coating layer formed of binderresin in which coating layer particles are embedded, bonded, and/orpartially absorbed, wetting of the outer surface of an at leastpartially coated pellet causes binder in the at least one coating layerto solubilize enabling additional coating material to be applied tofurther coat the pellets. When at least partially coated and preferablysubstantially completely coated with at least one coating layer formedof liquid-soluble binder resin and coating material, the coated pelletsproduce a granular absorbent product whose coated pellets readilyself-clump together when wetted that is well suited for use as catlitter.

A preferred system for carrying out a method of processing granularabsorbent that coats granular absorbent during transport includes acoating material delivery system having a coating material containerthat holds coating material along with at least one coating materialdelivery conduit that delivers coating material to granular absorbentbeing transported to at least partially coat granular absorbent duringtransport. One preferred coating material delivery system has a tank orhopper configured to hold granular coating material with at least onecoating material delivery conduit configured to deliver granular coatingmaterial to liquid-absorbent pellets during transport of the pellets bythe pneumatic conveyor. In one such preferred coating material deliverysystem, at least one coating material delivery conduit delivers granularcoating material to a location adjacent the discharge of the extruder toat least partially begin coating pellets immediately after beingextruded and preferably within no more than a second or two after beingextruded.

Where the pneumatic conveyor duct inlet is disposed close enough to thedischarge of the extruder to transport substantially completely all ofthe pellets extruded by the extruder during extruder operation, at leastone coating material delivery conduit can be provided with a dischargeor nozzle disposed adjacent the duct inlet to deliver granular materialonto pellets as they are extruded and while the freshly extruded pelletsare being transported by the pneumatic conveyor into the duct inlet.Excess granular coating material that did not coat the freshly extrudedpellets enters the duct inlet with the pellets where both aretransported together in the duct enabling pellets to be coated with anyexcess granular coating material during transport through the ductduring the transport step.

Where the pneumatic conveyor duct inlet is in fluid-flow communicationwith an extruder discharge chamber disposed at the discharge end of theextruder, at least one coating material delivery conduit can be providedin fluid-flow communication with the discharge chamber having adischarge or nozzle disposed adjacent the extruder discharge to delivergranular coating material onto pellets as they are extruded and as thepellets are being transported by the pneumatic conveyor into the ductinlet. Excess granular coating material that did not coat the freshlyextruded pellets enters the duct inlet with the pellets where both aretransported together in the duct enabling pellets to be coated with anyexcess granular coating material during transport through the ductduring the transport step.

If desired, at least one coating material delivery conduit of such acoating material delivery system can be in fluid-flow communication withthe duct inlet and/or with the duct adjacent the inlet but downstreamthereof to deliver granular coating material at the duct inlet and/oradjacent the duct inlet but downstream of the duct inlet. If desired,such a coating material delivery system constructed in accordance withthe present invention can have a plurality of coating material deliveryconduits with one or more configured to deliver granular coatingmaterial into the pneumatic conveyor duct at one or more spaced apartlocations downstream of the duct inlet. This enables additional granularcoating material to be added to pellets being transported in thepneumatic conveyor duct to further coat the pellets during such acoating step that is carried out during transport through the ductduring the transport step.

In a fifth preferred method implementation, a wetting step is performedduring the transport step where liquid-absorbent pellets are at leastpartially wetted with a wetting liquid during transport. Such a wettingliquid can include water and can also include one or more pellettreatment materials, including one or more pellet treatment materialsused to apply a scent, a flavor, an odor mask, an odor inhibitor, ananti-bacterial agent, an anti-fungal agent, and/or an anti-parasiticagent. In at least one wetting liquid used when a wetting step iscarried out during or after a coating step to help facilitate coating ofthe pellets during the transport step, the wetting liquid can be orotherwise include water. In one preferred wetting step carried outduring or after a coating step, the wetting liquid can include water andone or more of the aforementioned pellet treatment materials.

In another preferred wetting step, wetting liquid can include a binder,such as a water-soluble adhesive, which is also applied to the pelletsbeing wetted during the wetting step. Suitable water-soluble bindersthat can be mixed into and applied with wetting liquid during thewetting step onto the pellets include starch-based or starch-containingwater-soluble binders, dextrin, dextrin containing binders,dextrin-based binders, water-soluble bioadhesives, and/or other suitablewater-soluble binders. In such a wetting step that includes applicationof a water-soluble adhesive mixed with the wetting liquid, the wettingliquid mixture can also include one or more pellet treatment materialsused to apply a scent, a flavor, an odor mask, an odor inhibitor, ananti-bacterial agent, an anti-fungal agent, and/or an anti-parasiticagent such as described above.

In one preferred wetting step method implementation, a wetting step isperformed during a transport step after a drying step has begun to beperformed. In another preferred wetting step method implementation, awetting step is performed during or after a cooling step has begun to beperformed. In still another preferred wetting step methodimplementation, a wetting step is performed during the transport stepafter a coating step has begun to be performed and can be performedwhile the surface preparation step is performed.

A preferred system for carrying out a method of processing granularabsorbent that wets granular absorbent during transport includes awetting liquid delivery system having a wetting liquid container thatholds wetting liquid along with at least one wetting liquid deliveryconduit that delivers wetting liquid to granular absorbent beingtransported to at least partially wet granular absorbent duringtransport. One preferred wetting liquid delivery system has a tank orother container configured to hold wetting liquid with at least onewetting liquid delivery conduit configured to deliver wetting liquid toliquid-absorbent pellets during transport of the pellets by thepneumatic conveyor. In one such preferred wetting liquid deliverysystem, at least one wetting liquid delivery conduit delivers wettingliquid to a location downstream of the discharge of the extruder to atleast partially wet pellets more than a second or two after beingextruded.

At least one wetting liquid delivery conduit can be provided with adispenser, discharge or nozzle disposed adjacent the duct inlet todeliver wetting into the duct inlet as pellets are entering the ductinlet. A plurality of wetting liquid delivery conduits can be providedto deliver wetting liquid in the conduit during pellet transport at aplurality of longitudinally or axially spaced apart locations along theduct. Excess wetting liquid not immediately wetting pellets beingtransported in the duct is transported in the duct together with thepellets where the excess liquid can contact and wet pellets duringtransport through the duct.

Where a wetting step is being performed in conjunction with a coatingstep, wetting liquid preferably is delivered to the conduit downstreamof a location where coating materiel is delivered. Where coatingmaterial is delivered at a plurality of spaced apart locations, such asat one location adjacent the extruder discharge and another location inthe pneumatic conveyor duct, the wetting liquid delivery systempreferably is configured with a plurality of wetting liquid deliveryconduits with one of the wetting liquid delivery conduits deliveringwetting liquid into the duct downstream of where coating material isintroduced adjacent the extruder discharge and another one of thewetting liquid deliver conduits delivers wetting liquid into the ductdownstream of where coating material is delivered into the duct.

Where a wetting step is performed in conjunction with a coating stepduring pellet transport, coating material is first applied onto pelletsbeing transported before wetting liquid is applied as needed to wet atleast partially coated pellets to solubilize the outer binder resinlayer enough to tackify the outer pellet surface enabling additionalcoating material to be delivered to adhere to the tacky outer pelletsurface to further coat the pellet. Such coating and wetting steps canbe repeated and/or alternated as needed to increasingly further coatpellets as they are transported by the pneumatic conveyor during thetransport step thereby building up the pellet coating with additionallayers of coating material and/or resin binder and/or making thicker atleast one coating layer.

In summary, in one preferred pneumatic conveyor pellet transport andprocessing system, as the moisture content of the freshly extruded moistpellets of granular absorbent is reduced, the overall size and overallshape of each pellet is retained, including after performing any surfacepreparation, e.g., abrasive polishing, of the pellets. This isparticularly important to help produce a desirably low density finishedgranular absorbent product whether the pellets are coated or used inuncoated form. This is particularly important because reducing themoisture content of the pellets of granular absorbent in a controlledmanner within a desired moisture content range, such as a moisturecontent range of between 5% and 15% and preferably between 7% and 13%,control of the density of the finished absorbent product is therebyachieved. As a result, the profitability of a preferred granularabsorbent product well suited for use as cat litter is maximized by theproduction of a low-density granular absorbent by controlling pelletmoisture content. Carrying out a surface preparation step, e.g.,abrasive polishing step, before and/or in conjunction with drying of thegranular absorbent also helps control final absorbent product densitywhere coated to keep it desirably low as abrasive surface preparationhelps minimize the amount of coating applied to each pellet of thegranular absorbent product. Similarly, such low density granularabsorbent control can be and preferably also is employed to produce alow density granular absorbent used in oil spill remediation thatadvantageously allows for higher loading of the granular absorbent withheavier molecular weight surfactants and/or oil treatment materialswithout the granular absorbent product losing buoyancy in water (whethercoated or uncoated).

These and other objects, features and advantages of this invention willbecome apparent from the following detailed description of the inventionand accompanying drawings.

DRAWING DESCRIPTION

One or more preferred exemplary embodiments of the invention areillustrated in the accompanying drawings in which like referencenumerals represent like parts throughout and in which:

FIG. 1A illustrates a schematic diagram of a first preferred system fortreating granular absorbent during granular absorbent transport from anextruder using a pneumatic conveyor;

FIG. 1B illustrates a schematic diagram of a second preferred systemconfigured to carry out at least one of a drying step and a surfacepreparation step during granular absorbent transport from an extruderusing a pneumatic conveyor;

FIG. 2A illustrates a schematic diagram of a third preferred system fortreating granular absorbent during granular absorbent transport from anextruder using a pneumatic conveyor;

FIG. 2B illustrates a schematic diagram of a fourth preferred system fortreating granular absorbent during granular absorbent transport from anextruder using a pneumatic conveyor;

FIG. 3A illustrates a schematic diagram of a fifth preferred system fortreating granular absorbent during granular absorbent transport from anextruder using a pneumatic conveyor;

FIG. 3B illustrates a schematic diagram of a sixth preferred system forfor treating granular absorbent during granular absorbent transport froman extruder using a pneumatic conveyor;

FIG. 4A illustrates a schematic diagram of a seventh preferred systemfor treating granular absorbent during granular absorbent transport froman extruder using a pneumatic conveyor;

FIG. 4B illustrates a schematic diagram of an eighth preferred systemfor treating granular absorbent during granular absorbent transport froman extruder using a pneumatic conveyor;

FIG. 5A illustrates a first preferred but exemplary section of duct orductwork of a pneumatic conveyor in which uncoated granular absorbentpellets carried in air flowing through the duct abrasively treats thepellets in carrying out a preferred pellet outer surface treatmentmethod forming a plurality of pairs of smaller sized fines of granularabsorbent during pellet transport;

FIG. 5B illustrates a second preferred but exemplary section of duct orductwork of a pneumatic conveyor in which uncoated granular absorbentpellets carried in air flowing through the duct abrasively treats thepellets in carrying out another preferred pellet outer surface treatmentmethod that forms a plurality of pairs of smaller sized fines ofgranular absorbent during pellet transport;

FIG. 6A illustrates the first preferred but exemplary elongate sectionof pneumatic conveyor duct or ductwork of FIG. 5A depicting flow ofuncoated granular absorbent pellets and particles of coating materialentrained in air flowing through the duct forming fines in carrying outstill another preferred pellet outer surface treatment method where thepellets are at least partially coated with the coating material whileabsorbent fines are formed; and

FIG. 6B illustrates the second preferred but exemplary elongate sectionof duct or ductwork of FIG. 5B depicting flow of uncoated granularabsorbent pellets and particles of coating material entrained in airflowing through the duct forming fines in carrying out a furtherpreferred pellet outer surface treatment method where the pellets are atleast partially coated with the coating material while absorbent finesare formed.

Before explaining one or more embodiments of the invention in detail, itis to be understood that the invention is not limited in its applicationto the details of construction and the arrangement of the components setforth in the following description or illustrated in the drawings. Theinvention is capable of other embodiments, which can be practiced orcarried out in various ways. Also, it is to be understood that thephraseology and terminology employed herein is for the purpose ofdescription and should not be regarded as limiting.

DETAILED DESCRIPTION

With initial reference to FIGS. 1A and 1B, the present invention isdirected to a system 40 for treating or processing uncoated granularabsorbent 42 preferably with a coating material 43 as the uncoatedgranular absorbent 42 is being transported or conveyed via a gastransport conveyor 44, preferably a pneumatic conveyor 46, from anextruder 48 that extrudes the uncoated granular absorbent 42 to alocation 50 downstream of the extruder 48. As is discussed in moredetail below, the pneumatic conveyor 46 has an elongate tubular conduit52 that extends from the extruder 48 to the downstream location 50 wherecoating material 43 transported together with granular absorbent 42 inthe conduit 52 coats the granular absorbent 42 as the granular absorbent42 is conveyed by gas, e.g., air, flowing through the conduit 52 towardthe downstream location 50.

The extruder 46 is a single screw extruder or twin screw extruder thatis configured to (a) gelatinize, melt and/or degrade a starch-based orstarch-containing admixture that can include a fiber that can be and/orinclude insoluble fiber, and (b) extrude the gelatinized admixtureforming at least a plurality of pairs, i.e., at least three, of uncoatedgranules or pellets 42 of a starch-based or starch-containing absorbent.In one preferred granular absorbent, the starch-based orstarch-containing admixture is formed of at least one cereal grain thatcan be mixed with fiber that is extruded by the extruder 46 as anextrudate at a sufficiently high extrusion rate producing at least aplurality of pairs, i.e., at least three, of uncoated absorbent granulesor pellets 42 from the extrudate per second when the extrudatedischarged from the extruder 46 is cut by a rotary knife or cutter (notshown) of the extruder 46.

One preferred uncoated granular absorbent 42 formed of an extrudateproduced from an admixture includes starch-containing corn that can beand preferably is mixed together with at least five percent fiber bytotal dry admixture weight. The corn can be in the form of whole graincorn and/or degermed corn that can be provided in a ground or comminutedform as corn grits, corn meal, corn flour and/or cornstarch. Where sucha granular absorbent forming admixture includes fiber, the fiber can bewood fiber, rice fiber, oat fiber, wheat fiber and/or another type offiber that contains at least ten percent insoluble fiber by total dryfiber weight of the fiber added to the admixture. Such a fibercontaining admixture advantageously produces uncoated granules orpellets 42 of an absorbent material that is well suited for absorbingliquid, the fiber extruded in each absorbent granule or pellet 42advantageously reinforces each uncoated granule or pellet 42 making eachgranule or pellet tougher, more resilient, and more able to withstandimpact, shear, and wetting of the granules or pellets during coating,other treatment or processing, and/or use of the granular absorbentfinished product. Where the granules or pellets 42 are intended to becoated, such as with coating material, e.g., a smectite such asbentonite, the granular or pellets 42 provide a lightweight core thatcan have at least a plurality of pairs, i.e. at least three, of densityreducing voids and/or at least a plurality of pairs, i.e. at leastthree, of absorption increasing and/or density reducing pores formedtherein to which coating material is applied to coat the lightweightcores.

Another preferred uncoated granular absorbent 42 formed from extrudateproduced from an admixture includes starch-containing sorghum that canalso include at least five percent fiber by total dry admixture weight.One such preferred admixture preferably contains between five percentand thirty percent fiber. Another such preferred admixture contains nomore than twenty five percent. The sorghum can be red and/or whitesorghum in the form of whole grain sorghum and/or degermed sorghum thatcan be provided as the admixture and/or added to the admixture in aground or comminuted sorghum meal, sorghum grits, sorghum flour and/orsorghum starch form. Tannins in such a sorghum-containing admixture forma tannin containing extrudate that is formed into tannin-containinguncoated absorbent granules or pellets 42 advantageously provide thegranules or pellets 42 with increased resistance to bacterial growth,fungal growth, yeast growth, and/or virus growth when wetted withliquid. Where such a sorghum-containing admixture also includes fiber,the fiber can be wood fiber, rice fiber, oat fiber, wheat fiber oranother type of fiber that contains at least five percent insolublefiber by total dry fiber weight of the fiber added to the admixture. Onepreferred admixture contains between five percent and thirty percentinsoluble fiber. Another preferred admixture contains between fivepercent and twenty five percent insoluble fiber.

Granules or pellets 42 extruded from the extruder 46 are absorbent intheir uncoated form in that they possess an increased affinity forabsorbing a fluid that preferably is a liquid. In one embodiment, atleast a plurality of pairs, i.e., at least three, of uncoated liquidabsorbent granules or pellets 42 are discharged from the extruder 46during each second of operation the extruder 46 with each uncoatedliquid absorbent granule or pellet 42 having at least a plurality ofpairs of pockets or voids (not shown) formed therein that can beair-filled which can and preferably does help increase liquid absorptionof each uncoated liquid absorbent granule or pellet 42. Each uncoatedabsorbent granule or pellet 42 can also be of porous construction witheach uncoated granule or pellet 42 having at least a plurality of pairsof pores (not shown) formed in an outer surface (also not shown) of eachuncoated absorbent granule or pellet 42. Such uncoated liquid absorbentgranules or pellets 42 are advantageously well suited for use inabsorbing a plurality of different types of liquids including water,urine, liquid fecal matter, and/or liquefied fecal matter,volatile-containing liquids, hydrocarbon-containing liquids, motor oil,gasoline, diesel fuel, fuel oil, kerosene, crude oil, toxic liquidwaste, and/or one or more other types of liquid.

In one uncoated granular absorbent granule or pellet embodiment wellsuited for use in absorbing urine and/or fecal matter, the extruder 46is operated within a temperature range and/or pressure range that formsat least some water soluble starch-based binder in each extrudeduncoated absorbent granule or pellet 42 producing self-clumping uncoatedliquid absorbent granules or pellets 42 that tend to clump, e.g.,self-clump, together when wetted with liquid. In one preferredself-clumping granular absorbent granule or pellet embodiment, eachuncoated self-clumping liquid-absorbent granule or pellet 42 is composedof at least 7% water soluble starch-based binder by uncoated pelletweight that preferably includes at least 5% cold water soluble starchbinder by uncoated pellet weight. In another preferred self-clumpinggranular absorbent granule or pellet embodiment, each uncoatedself-clumping liquid-absorbent granule or pellet 42 is composed of atleast 15% water soluble starch-based binder by uncoated pellet weightthat preferably includes at least 10% cold water soluble starch binderby uncoated pellet weight. In yet another preferred self-clumpinggranular absorbent granule or pellet embodiment, each uncoatedself-clumping liquid-absorbent granule or pellet 42 has at least 15%cold water soluble starch binder by uncoated pellet weight.

In one such uncoated self-clumping liquid-absorbent granule or pelletembodiment, at least some, preferably at least 1%, of the water solublestarch-based binder of each uncoated self-clumping liquid-absorbentgranule or pellet 42 is dextrin by uncoated pellet weight. In onedextrin-containing uncoated granular absorbent granule or pelletembodiment well suited for use in absorbing urine and/or fecal matter,the extruder 46 is operated within a temperature range and/or pressurerange that causes dextrinization to occur during extrusion forming atleast 2% liquid soluble dextrin by pellet weight in each uncoatedextruded absorbent granule or pellet 42 thereby producing self-clumpingliquid absorbent granules or pellets 42 that self-clump together whenwetted with liquid.

Each uncoated absorbent granule or pellet 42 can be round or sphericalhaving a width or diameter of no greater than 6 millimeters and alength, such as where not round or spherical, of no greater than about 6millimeters. In one uncoated absorbent granule or pellet embodiment,each uncoated absorbent granule or pellet 42 has a width or diameter ofno greater than about 6 millimeters (5 millimeters±25%) and has a lengthor thickness, where not round or spherical, of no greater than about 3millimeters (two millimeters±25%). In one preferred uncoated absorbentgranule or pellet embodiment, each uncoated absorbent granule or pellet42 has a width or diameter of no greater than 5 millimeters and athickness of no greater than 2 millimeters with each uncoated absorbentgranule or pellet 42 having at least one of a disc or disk shape, acupped or concave disc or disk shape, a half-moon shape, a footballshape, and/or a shaped like a flake. In one preferred uncoated absorbentgranule or pellet embodiment, each uncoated granule or pellet 42 is aflake or shaped like a flake with each such uncoated absorbent flakehaving a width or diameter between 1 millimeter and 4.5 millimeters anda thickness of between ¼millimeter and 2 millimeters. In anotherpreferred uncoated absorbent granule or pellet embodiment, each uncoatedgranule or pellet 42 is a flake or shaped like a flake with each suchuncoated absorbent flake having a width or diameter between 1.5millimeters and 4 millimeters and a thickness of between ¼millimeter and1.75 millimeters. Each such uncoated absorbent flake, e.g., flake-shapedgranule or pellet 42, can be generally circular, generallysemi-circular, and/or generally half-moon shaped, football shaped, andcan also be generally flat, generally dish-shaped, generally concave,and/or generally cupped.

In one uncoated granular absorbent granule or pellet embodiment wellsuited for use in absorbing liquid that can be extruded as uncoatedabsorbent flakes and/or uncoated generally flake-shaped granules orpellets 42, each such uncoated liquid-absorbent flake, granule or pelletpreferably is coated with at least one layer of a coating material 43that preferably is a granular coating material 43 having a compositionconfigured to increase liquid absorption, treat absorbed liquid, and/ortime delay release or delivery of a treatment contained within the innergranule or pellet 42 coated with coating material 43, whilesubstantially completely encapsulating each granule or pellet 42 with anouter layer of coating material 43. Such a coating material 43 can beformed of and/or otherwise include a smectite, such as a smectite formedat least in part by or of a clay, which can be a bentonite clay, such asa sodium bentonite, calcium bentonite and/or another similar clay orclay-like material containing Montmorillonite. Such a coating material43 can further include one or more of the following: carbonate, e.g.,calcium carbonate and/or sodium carbonate, bicarbonate, e.g., calciumbicarbonate and/or sodium bicarbonate, salt, e.g., sodium chlorideand/or calcium chloride, silica, e.g., crystalline silica or quartz,and/or a zeolite, a binder, a scent, an odor inhibitor, an antifungal,an anti-parasitic, and/or another constituent. Where the coatingmaterial includes a binder, it preferably is in a dried granular, e.g.,powdered, form that is easily mixed with the rest of the coatingmaterial constituents disclosed herein. Where the coating materialincludes a binder, the binder can be a gum, such as guar gum, anacrylic, an acrylic-based binder, an acrylic-containing binder, astarch-based or starch-containing binder, a dextrin binder, adextrin-based or dextrin-containing binder, a bioadhesive, or anotherbinder that can be included, e.g., mixed with coating material that isapplied to granules or pellets 42 during the coating step at leastpartially coating the granules or pellets 42 with a coating materialcontaining binder that facilitates or enables self-clumping of aplurality of granules or pellets 42 when wetted during absorbent use.Such binders preferably are mixed with the other coating materialconstituents in granular form, preferably dry granular form, and can bein powdered form, including where the coating material is provided in apowdered form, such as in accordance with that disclosed herein.

Such a coating material 43 preferably is applied to each absorbentgranule or pellet 42 to substantially completely coat or encapsulateeach granule or pellet 42 with at least one outer coating or layer ofthe coating material 43 that is at least one mil thick. In anothercoating embodiment, a coating material 43 that preferably is a granularcoating material 43 made of at least a plurality of pairs, i.e., atleast three, particles 43 of the granular coating material 43 thatpreferably is applied to each absorbent granule or pellet 42 tosubstantially completely coat or encapsulate each granule or pellet 42with an outer coating or layer of the coating material 43 that is atleast one micron thick. Such an outer layer or coating of coatingmaterial 43 preferably is formed of a granular coating material 43formed of a plurality of pairs of granules or particles 43 each having awidth or diameter less than one-tenth the average width or diameter ofthe uncoated absorbent granules or pellets 42 extruded by the extruder48.

One such preferred granular coating material 43 is a powdered coatingmaterial 43. One such preferred powdered coating material 43 has atleast a plurality of coating material particles 43 with a mesh size ofbetween 20 mesh (U.S.) and 325 mesh (U.S.). One preferred powderedcoating material 43 has a mesh size of at least 70 mesh (U.S.). Anotherpreferred powdered coating material 43 has at least one half of theparticles of powdered coating material 43 having a mesh of between 170mesh (U.S.) and 230 mesh (U.S.).

One such preferred extruded granular absorbent is extruded formingliquid-absorbent pellets 42 composed of starch-based orstarch-containing material and/or fiber that preferably includesinsoluble fiber, e.g., cellulose. Whether coated as described herein oruncoated, the liquid-absorbent pellets 42 preferably include binder inan amount sufficient in each pellet 42 to cause pellets 42 to readilyclump together when wetted by a liquid, such as water, urine, liquidfecal matter, or another waste or toxic liquid, thereby producingself-clumping liquid-absorbent pellets. Such a binder can be, but is notlimited to, a starch-based or starch-containing bioadhesive such as coldwater soluble starch binder, dextrin and/or a combination thereof,and/or a synthetic adhesive, such as an acrylic adhesive, which iscarried by, e.g., coated, and/or disposed in each pellet 42 in an amountsufficient to produce self-clumping liquid-absorbent pellets. The bindercan be or include a cold water soluble starch binder extruded in eachpellet 42 during granular absorbent extrusion and/or which is applied tothe pellets 42 after extrusion. In a preferred embodiment, the bindercan be or include a cold water soluble starch binder formed from starchin the admixture during extrusion that is formed in each pellet 42.

One such preferred granular absorbent is formed of extrudedliquid-absorbent pellets 42, extruded such as described herein, whichcan be uncoated or coated (such as in the manner described herein),possessing binder in an amount sufficient to produce clumps when wettedby liquid, such as water, urine, liquid fecal matter, or another wasteor toxic liquid, formed of at least a plurality of pairs, i.e., at leastthree, of pellets 42 in each clump with each clump possessing at least90% clump retention, preferably determined via standardized cat litterclump retention testing, and/or having a crush or compressive strengthof at least 25 pounds per square inch (PSI) and preferably at least 40PSI when the clump is substantially dry (i.e., has between 10% and 15%moisture by clump weight). Another such granular absorbent is formed ofcoated or uncoated liquid-absorbent pellets 42 having binder in anamount sufficient to produce clumps when wetted during use as a liquidabsorbent that possesses at least 92% clump retention and which alsohave a crush or compressive strength of at least 45 PSI after and/orwhen the clump is substantially dry (i.e., has between 10% and 15%moisture by clump weight). Still another such granular absorbent isformed of coated or uncoated liquid-absorbent pellets 42 having binderin an amount sufficient to produce clumps when wetted during use as aliquid absorbent that possesses at least 95% clump retention and whichalso have a crush or compressive strength of at least 50 PSI when theclump is substantially dry. Yet another such granular absorbent isformed of coated or uncoated liquid-absorbent pellets 42 having binderin an amount sufficient to produce clumps when wetted during use as aliquid absorbent that possesses at least 90% clump retention and whichalso have a crush or compressive strength of at least 65 PSI when theclump is substantially dry. Still yet another such granular absorbent isformed of coated or uncoated liquid-absorbent pellets 42 having binderin an amount sufficient to produce clumps when wetted during use as aliquid absorbent that possesses at least 95% clump retention and whichalso have a crush or compressive strength of at least 65 PSI when theclump is substantially dry.

Another such preferred granular absorbent is formed of liquid-absorbentpellets 42 extruded as described herein with the pellets 42, whetheruncoated or coated (such as in the manner described herein), havingwater-soluble binder in an amount sufficient to self-clump when wettedby liquid, such as when wetted by water, urine, liquid fecal matter, oranother waste or toxic liquid, producing clumps of pellets possessing atleast 90% clump retention and/or having a crush or compressive strengthof at least 25 PSI and preferably at least 40 PSI when the clump issubstantially dry. One such preferred granular absorbent formed ofcoated or uncoated liquid-absorbent water-soluble binder-containingextruded pellets 42 have an amount of such binder sufficient to produceclumps when wetted that possess at least 92% clump retention and have acrush or compressive strength of at least 45 PSI when the clump issubstantially dry. Another such preferred granular absorbent formed ofcoated or uncoated liquid-absorbent water-soluble binder-containingextruded pellets 42 have an amount of such binder sufficient to produceclumps when wetted that possess at least 95% clump retention and have acrush or compressive strength of at least 50 PSI when the clump issubstantially dry. Yet another such preferred granular absorbent formedof coated or uncoated liquid-absorbent water-soluble binder-containingextruded pellets 42 have an amount of such binder sufficient to produceclumps when wetted that possess at least 90% clump retention and have acrush or compressive strength of at least 65 PSI when the clump issubstantially dry. Still yet another such preferred granular absorbentformed of coated or uncoated liquid-absorbent water-solublebinder-containing extruded pellets 42 have an amount of such bindersufficient to produce clumps when wetted that possess at least 90% clumpretention and have a crush or compressive strength of at least 65 PSIwhen the clump is substantially dry. In at least one such embodiment,each extruded pellet 42 contains at least 10% water soluble binder. Inanother such embodiment, each extruded pellet 42 contains at least 15%water soluble binder. In still another embodiment, each extruded pellet42 contains at least 20% water soluble binder. In still anotherembodiment, each extruded pellet 42 contains at least 25% water solublebinder. In a further embodiment, each extruded pellet 42 contains atleast 30% water soluble binder.

Still another such preferred granular absorbent is formed ofliquid-absorbent pellets 42 extruded as described herein forming pellets42, whether uncoated or coated (such as described herein), having coldwater soluble starch binder in an amount sufficient to self-clump whenwetted by liquid, such as water, urine, liquid fecal matter, or anotherwaste or toxic liquid, producing clumps possessing at least 90% clumpretention and/or having a crush or compressive strength of at least 25PSI and preferably at least 40 PSI when the clump is substantially dry.Another such preferred granular absorbent formed of coated or uncoatedliquid-absorbent water-soluble bioadhesive binder-containing pellets 42have an amount of such binder sufficient to produce clumps when wettedpossessing at least 92% clump retention and having a crush orcompressive strength of at least 45 PSI when the clump is substantiallydry. Still another such preferred granular absorbent formed of coated oruncoated liquid-absorbent cold water-soluble bioadhesivebinder-containing pellets 42 have an amount of such binder sufficient toproduce clumps when wetted possessing at least 95% clump retention andhaving a crush or compressive strength of at least 50 PSI when the clumpis substantially dry. Yet another such preferred granular absorbentformed of coated or uncoated liquid-absorbent water-soluble bioadhesivebinder-containing pellets 42 have an amount of such binder sufficient toproduce clumps when wetted possessing at least 90% clump retention andhaving a crush or compressive strength of at least 65 PSI when the clumpis substantially dry. Still yet another such preferred granularabsorbent formed of coated or uncoated liquid-absorbent water-solublebioadhesive binder-containing pellets 42 have an amount of such bindersufficient to produce clumps when wetted possessing at least 95% clumpretention and having a crush or compressive strength of at least 65 PSIwhen the clump is substantially dry. In at least one such embodiment,each extruded pellet 42 contains at least 10% water soluble binder byuncoated pellet weight. In another such embodiment, each extruded pellet42 contains at least 15% water soluble binder by uncoated pellet weight.In still another embodiment, each extruded pellet 42 contains at least20% water soluble binder by uncoated pellet weight. In still anotherembodiment, each extruded pellet 42 contains at least 25% water solublebinder by uncoated pellet weight. In a further embodiment, each extrudedpellet 42 contains at least 30% water soluble binder. In a still furtherembodiment, each extruded pellet 42 contains at least 35% water solublebinder by uncoated pellet weight.

A first preferred embodiment of a granular absorbent conveyor andcoating system 40 a is shown in FIG. 1A that includes a gas transportconveyor 44 that preferably is a pneumatic conveyor 46 having anelongate tubular conduit 52 through which at least a plurality of pairs,i.e., at least three, uncoated granules or pellets 42 extruded persecond from the extruder 48 are transported via gas, e.g., air, flowingthrough the conduit 52 to a location 50 remote from the extruder 48 thatpreferably is a granular absorbent handling and/or processing station 60located downstream of the extruder 48. The granules or pellets 42 travelthrough the conduit 52 together with coating material 43 at leastpartially coating the granules or pellets 42 with coating material 43 asboth travel through the conduit 52. The pneumatic conveyor conduit 52has an inlet or intake 54 disposed at or adjacent one conduit end thatis in fluid-flow communication with a discharge end 56 of the extruder48. The conduit 52 has an outlet or discharge 58 disposed at or adjacentan opposite conduit end that can be in fluid-flow communication with agranular absorbent handling and/or processing station 60 disposed at thelocation 50 remote or downstream of the extruder 48.

A gas mover 62, such as in the form of a pump, compressor or blower 64,is in gas-flow communication with the conduit 52 causing gas, e.g., air,to flow through the conduit 52 at a flow rate sufficient to draw atleast a plurality of pairs, i.e., at least three, of granules or pellets42 of granular absorbent per second into the conduit inlet or intake 54where the flowing gas, e.g., flowing air, then transports the granulesor pellets 42 of granular absorbent entrained in the flowing gas, e.g.,flowing air, toward the conduit outlet or discharge 58. One preferredgas mover 62 is a fan or blower 64, such as a centrifugal blower orsquirrel cage blower, in gas-flow communication with the conduit 52upstream of the conduit outlet or discharge 58. If desired, the gasmover 62 can be a vacuum pump or the like disposed downstream of theconduit inlet or intake 54 that can be disposed in gas-flowcommunication with the conduit outlet or discharge 58 creating a vacuumat the conduit inlet or intake 54 that sucks the granules or pellets 42of granular absorbent into the inlet or intake 54 during operation.

An elongate blower pipe or hose 66 conveys gas, e.g., air, moved by thefan or blower 64 to the pneumatic conveyor conduit 52 with the blowerpipe or hose 66 shown in FIG. 1A in gas-flow communication, e.g.,air-flow communication, with the pneumatic conveyor conduit inlet orintake 54. As is further depicted in FIG. 1A, gas, e.g., air, from thefan or blower 64 is delivered via the pipe or hose 66 to the pneumaticconveyor conduit inlet or intake 54 upstream of the conduit inlet orintake 54 so as to cause uncoated granules or pellets 42 extruded fromthe extruder 48 to be directed into the conduit inlet or intake 54 asthey are being extruded.

During operation, gas, e.g., air, from the fan or blower 64 deliveredthrough pipe or hose 66 in gas-flow communication with the conduit inletor intake 54 causes uncoated granules or pellets 42 of granularabsorbent to be directed into the conduit inlet or intake 54substantially simultaneously as fast as the uncoated granules or pellets42 are extruded from the extruder 48. Preferably, at least a pluralityof pairs of uncoated granules or pellets 42 of granular absorbent aredrawn into the pneumatic conveyor conduit inlet or intake 54 per secondas a result.

With continued reference to FIG. 1A, the granular absorbent conveyor andcoating system 40 a includes an extrudate discharge chamber 68, e.g.,pellet collector or pellet collecting hopper, of the extruder 48 intowhich at least a plurality of pairs of uncoated granules or pellets 42of granular absorbent are extruded by the extruder 48 per second duringextruder operation. The extrudate discharge chamber 68 can andpreferably does substantially gas-tightly enclose the discharge end 56of the extruder 48. In a preferred embodiment, the chamber 68 can alsoinclude one or more selectively adjustable vents (not shown) that can beopened and/or selectively adjusted or regulated to control the rateand/or volume of flow of gas, e.g., air, entering or leaving the chamber68 during operation. The chamber 68 can be a box or other enclosureextending outwardly from and substantially completely enclosing thedischarge end 56 of the extruder 48 enclosing the discharge end 56 ofthe extruder 48 such that uncoated granules or pellets 42 of granularabsorbent extruded from or by the extruder 48 are extruded into thechamber 68 during extruder operation.

In the preferred embodiment of the granular absorbent conveyor andcoating system 40 a shown in FIG. 1A, both the pneumatic conveyorconduit inlet or intake 54 and the gas mover hose or pipe 66 are ingas-flow, e.g., air-flow, communication with the extrudate dischargechamber 68 with the pneumatic conveyor conduit 52 and gas mover hose orpipe 66 each connected or coupled to the chamber 68. During extruderoperation, gas, e.g., air, moved by the fan or blower 66 through the gasmover hose or pipe 66 is discharged from the hose or pipe 66 into theextrudate discharge chamber 68 causing gas, e.g., air, in turn to flowinto the pneumatic conveyor conduit inlet or intake 54 drawing uncoatedgranules or pellets 42 as they are extruded from the extruder 48 to bedrawn into the conduit inlet or intake 54. The gas, e.g., air,discharged from the hose or pipe 66 into chamber 68 creates a pressuredifferential inside the chamber 68 and conduit 52 relative to theambient pressure of the atmosphere, e.g., air, (“ambient atmosphericpressure”) outside the conduit 52 and chamber 68. This pressuredifferential can and preferably does create a partial vacuum at theconduit inlet or intake 54 which in turn causes the at least pluralityof pairs, i.e., at least three, of uncoated granules or pellets 42 ofgranular absorbent extruded by the extruder 48 per second to be suckedor drawn from the chamber 68 into the conduit inlet or intake 54.

As the granules or pellets 42 are drawn from the extruder 48 into theintake 54 of the conduit 52 the granules or pellets 42 are transportedthrough the conduit 52 preferably drying the granules or pellets 42 andcooling the granules or pellets 42 by turbulently flowing air carryingthe granules or pellets 42 through the conduit 52. As also disclosedelsewhere herein, the granules or pellets 42 are dried by reducing amoisture content of each granule or pellet 42 at least 1% by weight froman initial moisture content of the granules or pellets 42 entering theconduit 52 through the intake 54 to a final moisture content of thegranules or pellets 42 exiting an outlet 58 of the conduit 52. In onepreferred method, granule or pellet moisture content is reduced at least2% and preferably is reduced at least 3% from being dried duringtransport through the conduit 52. In another preferred method, granuleor moisture content is reduced at least 4%. In a still further preferredmethod, granule or moisture content is reduced at least 5%.

During transport, each extruded granule or pellet 42 also is cooledwhile being dried. In a preferred method, each granule or pelletpreferably is cooled at least 10 degrees Celsius and preferably at least15 degrees Celsius during pellet transport, preferably while also beingdried. In a preferred cooling step, each granule or pellet preferably iscooled at least 15 degrees Celsius to a temperature that is within 10degrees Celsius of room temperature, e.g., within 10 degrees Celsius of23 degrees Celsius. In another preferred cooling step, each granule orpellet preferably is cooled at least 25 degrees Celsius to a temperaturethat is within 10 degrees Celsius of room temperature, e.g., within 10degrees Celsius of 23 degrees Celsius. In still another preferredcooling step, each granule or pellet preferably is cooled at least 30degrees Celsius to a temperature that is within 10 degrees Celsius ofroom temperature, e.g., within 10 degrees Celsius of 23 degrees Celsius.

In a preferred method of substantially simultaneously cooling and dryinggranules or pellets 42 after being extruded from the extruder 48 duringtransport through the conduit 52, extruded granules or pellets 42 aresucked into the pneumatic conveyor intake 54 and dried by reducing theirmoisture content at least 1% and cooled at least 10 degrees Celsiusduring transport from the conduit intake 54 to the conduit outlet 58. Inanother preferred method of cooling and drying extruded granules orpellets 42 during pneumatic conveyor conduit transport, the granules orpellets 42 are dried by reducing granule or pellet moisture content atleast 1% by pellet weight and reducing granule pellet temperature atleast 15 degrees Celsius during transport through the conduit 52. Instill another preferred method of cooling and drying extruded granulesor pellets 42 during pneumatic conveyor conduit transport, the granulesor pellets 42 are dried by reducing granule or pellet moisture contentat least 1% by pellet weight and reducing granule pellet temperature atleast 20 degrees Celsius during transport through the conduit 52. Inanother preferred method of cooling and drying extruded granules orpellets 42 during pneumatic conveyor conduit transport, the granules orpellets 42 are dried by reducing granule or pellet moisture content atleast 1% by pellet weight and reducing granule pellet temperature atleast 30 degrees Celsius during transport through the conduit 52.

In another preferred method of substantially simultaneously cooling anddrying granules or pellets 42 after being extruded from the extruder 48during transport through the conduit 52, extruded granules or pellets 42are sucked into the pneumatic conveyor intake 54 and dried by reducingtheir moisture content at least 2% and cooled at least 10 degreesCelsius during transport from the conduit intake 54 to the conduitoutlet 58. In another preferred method of cooling and drying extrudedgranules or pellets 42 during pneumatic conveyor conduit transport, thegranules or pellets 42 are dried by reducing granule or pellet moisturecontent at least 2% by pellet weight and reducing granule pellettemperature at least 15 degrees Celsius during transport through theconduit 52. In still another preferred method of cooling and dryingextruded granules or pellets 42 during pneumatic conveyor conduittransport, the granules or pellets 42 are dried by reducing granule orpellet moisture content at least 2% by pellet weight and reducinggranule pellet temperature at least 20 degrees Celsius during transportthrough the conduit 52. In another preferred method of cooling anddrying extruded granules or pellets 42 during pneumatic conveyor conduittransport, the granules or pellets 42 are dried by reducing granule orpellet moisture content at least 2% by pellet weight and reducinggranule pellet temperature at least 30 degrees Celsius during transportthrough the conduit 52.

Air preferably is drawn from ambient outside the extruder 48 and conduit52 by the pneumatic conveyor with the ambient air preferably having atemperature no greater than 32 degrees Celsius and preferably having atemperature of about room temperature, e.g., between 20-24 degreesCelsius. Air flowing through the conduit 52 during cooling and drying ofthe granules or pellets 42 carried by the air preferably has atemperature no greater than 50 degrees Celsius and preferably has atemperature less than 45 degrees Celsius at or adjacent, e.g.,downstream of the inlet or intake 54 of the conduit 52. In a preferredmethod, the air flowing through the conduit 52 preferably has an averagetemperature no greater than 30 degrees Celsius and preferably has anaverage temperature no greater than about 27 degrees Celsius.

Such drying and cooling of the granules or pellets 42 as the granules orpellets 42 are being transported through the conduit 52 advantageouslyreduces granule or pellet shrinkage while also preventing densityincreases that can be viewed as undesirable. Such drying and cooling ofthe granules or pellets 42 also advantageously prevents loss of watersoluble binder including by preventing loss of cold water soluble starchbinder in each granule or pellet 42 that can occur after extrusion ifnot cooled and dried. Finally drying of the granules or pellets 42 isadvantageously done using air at ambient temperatures, e.g., between 20degrees Celsius and 24 degrees Celsius thereby drying and coolingwithout heating or using an oven to heat and dry the granules or pellets42 thereby “cool drying” the granules or pellets 42 in fewer steps andusing less energy. The above amounts or percentages of cooling anddrying of the granules or pellets 42 during transport through thepneumatic conveyor conduit 52 are preferably also achieved substantiallysimultaneously during coating, wetting, liquid treatment and/or surfacetreatment to form smaller sized fines 164 of granular absorbentdisclosed in more detail below.

If desired, the granular absorbent conveyor and coating system 40 a caninclude a gas knife system 70 that preferably is an air knife system 72that includes another gas mover 74 that preferably is a gas compressor76, e.g., air compressor, which delivers gas, e.g., air, through anelongate tube or pipe 78 at a pressure greater than the ambientatmospheric pressure directed at or toward the discharge end 56 of theextruder 48 to help encourage uncoated granules or pellets 42 extrudedby the extruder 48 into the pneumatic conveyor conduit inlet or intake54 preventing the extruded granules or pellets 42 from accumulating inthe extrudate discharge chamber 68 and/or becoming stuck to part of thechamber 68 and/or part of the extruder 48. Although not shown in FIG.1A, a preferred embodiment of such an air knife system 72 can include agas nozzle 73, e.g. air knife, in gas-flow, e.g., air-flow,communication with tube or pipe 78 and the extrudate discharge chamber68 directing a stream of pressurized gas, e.g., air, towards or at aperforate extrusion die (not shown) disposed at the discharge end 56 ofthe extruder 48 from which the uncoated granules or pellets 42 ofgranular absorbent are extruded. Such an air knife 73 can be or includean elongate or linear nozzle 73 in gas-flow, e.g. air-flow,communication with the interior of the chamber 68 to direct a sheet ofgas, e.g., air toward the extrusion die of the extruder 48 and/or anyother location within the chamber 68 where extruded granules or pellets42 tend to accumulate and/or stick to prevent such from happening.

With continued reference to FIG. 1A, the granular absorbent conveyor andcoating system 40 a further includes a coating material delivery system80 that includes a source of coating material 82 where coating material43 is held in a hopper or tank 81 with the coating material 43 deliveredto the pneumatic conveyor 46 by an elongate conduit 84. During operationof the coating material delivery system 80, coating material 43 from thehopper or tank 81 is delivered by the coating material delivery conduit84 to a location at or adjacent the discharge end 56 of the extruder 48and/or pneumatic conveyor conduit 52 causing coating material 43 to betransported in the conduit 52 together with granules or pellets 42 ofgranular absorbent at least partially coating the granules or pellets 42with coating material 43 as the granules or pellets 42 travel throughconduit 52 toward the location 50 remote or downstream of the extruder48.

The coating material delivery conduit 84 is connected to the extrudatedischarge chamber 68 adjacent and/or upstream of the pneumatic conveyorconduit inlet or intake 54 such that coating material 43 discharged fromthe conduit 84 into the chamber 68 is sucked or otherwise drawn throughthe inlet or intake 54 into the pneumatic conveyor conduit 52 along withgranules or pellets 42 extruded from the extruder 48. Coating material43 is entrained together with granules or pellets 42 in the gas, e.g.,air, flowing in the conduit 52 with granules or pellets 42 coming intocontact with coating material 43 at least partially coating granules orpellets 42 with a layer of coating material 43 as the granules orpellets 42 are being transported in the conduit 52 toward the granularabsorbent handling and/or processing station 60 disposed at the location50 remote or downstream of the extruder 48.

Where the extruded granules or pellets 42 are still tacky, such as bystill being moist after extrusion, coating material 43 flowing in theair stream inside conduit 52 with the granules or pellets 42 adheres tothe granules or pellets 42 coating the granules or pellets 42 with thecoating material 43 at least partially coating the pellets or granules42. In a preferred granule or pellet embodiment, granules or pellets 42having a liquid soluble binder which are tacky enable coating material43, e.g. in particulate or granular form, to stick to the tacky outersurface of each granule or pellet 42 with wetted binder on the outersurface of each granule or pellet 42 acting as an adhesive that bindsthe coating material 43 to the pellet outer surface. As the coatingmaterial 43 adheres to the tacky outer pellet surface, wetted binder onthe outer surface of each granule or pellet 42 glues coating material tothe outer granule or pellet surface forming an outer granule or pelletlayer composed of coating material 43 and binder that cures and hardensas the binder dries locking the coating material 43 in place. As thecoating material 43 adheres to the wetted binder on the tacky outersurface of each granule or pellet 42, the coating material 43 dries atleast the tacky outer surface of the granule or pellet 42 thereby morerapidly curing the wetted binder in the tacky outer surface of thegranule or pellet 42 in a pellet coating step that advantageously alsois a pellet drying step.

Delivery of coating material 43 from hopper or tank 81 can be viagravity feed, pressure feed, pneumatic feed, screw or auger feed, and/orusing another type of feed. A nozzle, valve, or the like which can bemanually and/or selectively controlled and/or regulated can be employedat or adjacent the end of the coating material delivery conduit 84 thatis connected, e.g., in gas-flow or air-flow communication, with theextrudate discharge chamber 68 to meter or otherwise regulate the rateand/or amount of coating material 43 delivered into the chamber 68 bythe coating material delivery system 80. In one preferred embodiment,the coating material 43 is a granular coating material, such inaccordance with one or more formulations of the granular coatingmaterial 43 discussed hereinabove that can be provided in a dry powderedcoating material format.

The granular absorbent conveyor and coating system 40 a can furtherinclude a wetting system 86 having a source of wetting material 88 thatpreferably is a liquid, e.g., water, held in a container 90 that can bea hopper or tank 92 from which the wetting liquid is delivered via anelongate conduit 94 to the coating material delivery conduit 84, theextrudate discharge chamber 68, and/or the pneumatic conveyor conduit52, such as is depicted in phantom in FIGS. 1A and/or 1B. In onepreferred wetting system implementation shown in FIG. 1A, wetting liquidcan be delivered via a branch 94 a of the wetting liquid deliveryconduit 94 into the extrudate discharge chamber 68 at or adjacent wherethe coating material delivery conduit 84 delivers coating material intothe chamber 68 with one or both the coating material 43 and wettingliquid thereby being delivered into the chamber 68 upstream of thepneumatic conveyor conduit inlet or intake 54. Although not shown inFIG. 1A, branch 94 a of the wetting liquid delivery conduit 94preferably introduces wetting liquid into the extrudate dischargechamber 68 at a location different than the location where the coatingmaterial delivery conduit 84 delivers coating material into the samechamber 68. In one such preferred implementation, branch 94 a introduceswetting liquid into the chamber 68 downstream of where coating materialis introduced by the coating material delivery conduit 84 into thechamber 68 but upstream of the pneumatic conveyor conduit inlet orintake 54. In another such preferred implementation, branch 94 aintroduces wetting liquid into the chamber 68 upstream of the pneumaticconveyor conduit inlet or intake 54 and upstream of where coatingmaterial 43 is introduced into the chamber 68 via the coating materialdelivery conduit 84.

If desired, the wetting material delivery conduit 94 can deliver wettingliquid directly into the pneumatic conveyor conduit 52 via a differentbranch 94 b that is connected to the pneumatic conveyor conduit 52downstream of the conduit inlet or intake 54 and downstream of theextrudate discharge chamber 68 in another preferred wetting systemimplementation. In a still further wetting system implementation, thewetting material conduit 94 can have a plurality of branches 94 a and 94b enabling wetting liquid to be introduced substantially simultaneouslyand/or alternately with coating material 43 into the pneumatic conveyorconduit 52 downstream of the conduit inlet or intake 54 and/or intoextrudate discharge chamber 68.

Delivery of wetting liquid from the hopper or tank 92 can be via gravityfeed, pressure feed, pump feed, pneumatic feed, screw or auger feed,and/or using another type of feed. A nozzle, valve, dispenser, or thelike, which can be manually and/or selectively controlled and/orregulated, can be disposed at or adjacent the end of the wetting liquiddelivery conduit 94, such as where the conduit 94 is connected, e.g., ingas-flow or air-flow communication, with the extrudate discharge chamber68 and/or pneumatic conveyor conduit 52. This can be done to meter orotherwise regulate the rate and/or amount of wetting liquid deliveredinto the chamber 68 and/or conduit 52 by the wetting liquid deliverysystem 86. In one preferred embodiment, the wetting liquid is orincludes water that can be delivered in the form of a stream and/or mistinto chamber 68 and/or conduit 52 to at least partially wet granules orpellets 42 of granular absorbent being transported together with coatingmaterial in conduit 52 helping to facilitate at least partial coating ofthe granules or pellets 42 during transport in conduit 52.

During application of wetting liquid during the wetting step,liquid-absorbent pellets 42 are at least partially wetted with a wettingliquid during transport during at least a portion of the transport step.Such a wetting liquid can include water and can also include one or morepellet treatment materials mixed therewith, such as one or more pellettreatment materials used to scent, flavor, provide odor masking, providean odor inhibitor, provide an anti-bacterial agent, provide ananti-fungal agent, and/or provide an anti-parasitic agent. In at leastone wetting liquid used when a wetting step is carried out during orafter a coating step to help facilitate coating of the pellets duringthe transport step, the wetting liquid can be or otherwise includewater. In one such preferred wetting step carried out during or after acoating step, the wetting liquid includes water and one or more of thepellet treatment materials disclosed herein.

The wetting liquid can include a binder, such as a water-solubleadhesive, which is also applied to the pellets 42 being wetted duringthe wetting step during pellet transport together with the wettingliquid and/or can be mixed with the wetting liquid and applied with thewetting liquid. Suitable water-soluble binders that can be mixed intoand applied with wetting liquid during the wetting step onto the pelletsinclude starch-based or starch-containing water-soluble binders,dextrin, dextrin containing binders, dextrin-based binders,water-soluble bioadhesives, and/or other suitable water-soluble binders.In such a wetting step that includes application of a water-solubleadhesive mixed with the wetting liquid, the wetting liquid mixture canalso include one or more pellet treatment materials used to apply ascent, a flavor, an odor mask, an odor inhibitor, an anti-bacterialagent, an anti-fungal agent, and/or an anti-parasitic agent such asdescribed above.

As is also schematically depicted in FIG. 1A, the pneumatic conveyor 44discharges granules or pellets 42 that have been at least partiallycoated with granular coating material 43 during transport of thegranules or pellets 42 in the conduit 52. The at least partially coatedabsorbent granules or pellets 42 are discharged from the pneumaticconveyor conduit outlet or discharge 58 to a location 50 locateddownstream from the extruder 48 a distance away from the extruder 48that can be a handling and/or processing station 60. In the preferredstation embodiment shown in FIG. 1A, the station 60 is a coater 96 thatcoats absorbent granules or pellets 52. Where the granules or pellets 52have been at least partially coated by the granular absorbent conveyorand coating system 40 a, coater 96 further coats the granules or pellets42 preferably with additional coating material 43 that preferably is orincludes granular coating material 43 that can be or included powderedcoating material 43.

With continued reference to FIG. 1A, the coater 96 can be a rotaryagglomerator 98 that has a generally cylindrical rotary drum 100 thatcoats absorbent granules or pellets 52 inside the drum 100 with granularcoating material 43, preferably powdered granular coating material 43,added to the drum 100 while the drum 100 is rotating. One preferredrotary agglomerator 98 is a rotary seasoner coater 102 having a rotarydrum 100 that can be perforate that can also include a radiant and/orconvective dryer arrangement 104 used to dry or further dry at leastpartially coated absorbent granules or pellets 42 including while thegranules or pellets 42 are being coated with granular coating material43 inside the seasoner coater 102.

Such a seasoner can be modified as a coater 102 to coat absorbentgranules or pellets 42 by adding or including at least one granularcoating delivery arrangement 106 that preferably is or includes at leastone elongate longitudinally extending granular coating material deliverymanifold 108 extending axially within the rotary drum 100 of the coater96 with each manifold 108 having a plurality of spaced apart dischargedispensers or nozzles 110 from which granular coating material 43 isintroduced into the rotating drum 100 during coater operation. Such aseasoner coater 102 can be further modified to add or include at leastone wetting liquid delivery arrangement 112 (shown in phantom in FIG.1A) that preferably is or includes at least one elongate longitudinallyextending granular wetting liquid delivery manifold 114 extendingaxially within the rotary drum 100 of the coater 96 with each manifold114 having a plurality of spaced apart discharge dispensers or nozzles116 from which wetting liquid is introduced into the rotating drum 100during coater operation.

Where the drying arrangement 104 includes a convective dryingarrangement 118, the convective drying arrangement 118 can have anelongate generally longitudinally or axially extending manifold 120having a plurality of axially or longitudinally spaced apart outlets 122directing gas, preferably air, through and/or into the drum 100 duringcoater operation to dry the granules or pellets 42 by reducing theirmoisture content to a moisture content when discharged from the coater96 that is less than when the granules or pellets 42 enter the coater96. Such a convective drying arrangement 118 preferably includes a fan,compressor or blower 124 that delivers drying air through a conduit 126to the dryer manifold 120.

During rotary seasoner coater operation, the drum 100 is rotated whilegranules or pellets 42, which can have been at least partially coatedwith coating material 43 applied during transport in pneumatic conveyor44, are introduced through a coater inlet 130 into the rotating drum100. An amount of coating material 43, such as a granular, preferablypowdered, coating material 43 formulated in accordance with at least onesuch granular coating material 43 described above, is selectivelyintroduced, preferably in a predetermined amount or charge, through atleast one dispenser or nozzle 110 for a period of time, preferably apredetermined period of time, into the rotating drum 100 while thegranules or pellets 42 are inside the drum 100 causing granular coatingmaterial 43 to coat and/or, where the granules or pellets 42 are alreadyat least partially coated, further coat the granules or pellets 42 withgranular coating material 43.

In one seasoner coater embodiment and method of coating using a seasonermodified to coat granular absorbent, a first charge of powdered coatingmaterial 43 is introduced into the drum 100 of the seasoner coater 96through at least one dispenser or nozzle 110 while the rotating drum 100also has at least a plurality of pairs of granules or pellets 42 ofgranular absorbent in the drum 100. A first amount or charge of wettingliquid is introduced into the drum 100 of the seasoner coater 96 throughat least one dispenser or nozzle 116 during or following introductioninto the drum 100 of the first charge of the powdered coating material43 with the wetting liquid at least partially wetting the plurality ofpairs of granules or pellets 42 of granular absorbent causing powderedgranular coating material 43 to adhere or better adhere to at least aplurality of the plurality of pairs of granules or pellets 42. As theplurality of pairs of granules or pellets 42 travel through the rotarydrum 100 of the seasoner coater 96, at least a plurality of charges ofpowdered coating material 43 and at least a plurality of charges ormetered amounts of wetting liquid are substantially simultaneouslyand/or alternately introduced into the rotating drum 100 coating and/orat least further coating each one of the plurality of pairs of granulesor pellets 42 in the drum before the coated or further coated pluralityof pairs of granules or pellets 42 exit out a coater discharge 132.

During coater operation, a charge or metered amount of wetting liquid isapplied onto a plurality of pairs of granules or pellets 42 travelingthrough the drum 100 wetting the outer surface of each one of thegranules or pellets 42 causing each charge granular coating material 43introduced into the drum 100 to adhere or better adhere to the granulesor pellets 42. During wetting of the plurality of pairs of granules orpellets 42, liquid soluble starch-containing binder in an outer surfaceof each granule or pellet 42 is at least partially solubilized by and/orinto the wetting liquid creating a moist or wet gel or paste outergranule or pellet surface onto which particles of the granular coatingmaterial 43 stick. Repeated application of wetting liquid throughcarrying out a plurality of wetting liquid application cycles at one ormore longitudinally or axially spaced apart locations 110 within therotating drum 100 of the coater 96 causes at least a plurality of pairsof particles of the granular coating material 43 to be drawn into arelatively thin outer layer of the wetted starch-containing binder ofeach granule or pellet 42. By drawing out or teasing starch-containingbinder of each granule or pellet 42 through application of wettingliquid in a plurality of wetting liquid application cycles carried outwhile the granules or pellets 42 are traveling through the coater drum100, particles of granular coating material 43 become stuck to, enmeshedwithin and even solubilized by and/or into an outer layer or coating ofthe coating material 43 held together by a matrix of thestarch-containing binder.

When coating is completed, a thin outer layer or coating that is atleast one mil or micron thick substantially completely encapsulates eachone of the plurality of pairs of at least partially coated absorbentgranules or pellets 42 with the outer layer or coating formed of amatrix or resin of starch-containing binder in which particles of thegranular coating material 43 are attached and/or embedded. This producesan outer coating that substantially completely encapsulates each one ofthe plurality of pairs of coated granules or pellets 42 havingstarch-containing binder that readily wets in the presence of a liquid,such as urine, liquid fecal material, liquid waste, toxic liquid wastematerial, oil, gasoline, kerosene, crude oil, etc. which activatesand/or works in concert with the coating material 43 of the outer layeror coating of the coated granule(s) or pellet(s) 42 to better absorb theliquid during absorbent operation of the coated granules or pellets 42.The starch-containing binder that forms the coating matrix or binder ofthe outer layer or coating of each coated granule or pellet 42 in whichthe granular coating material 43 is attached and/or embedded, can andpreferably does flow when the coated granules or pellets 42 are wettedwith liquid during absorbent operation causing each wetted coatedgranule or pellet 42 to stick to or otherwise clump with at least aplurality of other coated granules or pellets 42 producing self-clumpinggranular absorbent operation.

While the rotary drum 100 of the seasoner coater 96 can be perforate, ahousing or enclosure surrounding the drum 100 can be imperforate so asto enable excess gas, such as from the pneumatic conveyor 44, to beintroduced into the drum 100 to reduce the moisture content of thegranules or pellets 42 as they pass through the coater 96 while they arebeing coated and/or further coated by granular coating material 43. Ifdesired, such a housing or enclosure can provide a substantially gastight, e.g., air tight, seal about the coater drum 100. Where the coater96 also is equipped with a drying arrangement 104, the dryingarrangement 104 can also be used during coater operation to dry granulesor pellets 42 being coated while excess gas, e.g., air, from thepneumatic conveyor 44 is also introduced into the coater 96.

If desired, part of the coater 96, such as part of its drum 100 and/orouter enclosure surrounding the drum 100 can have a drying arrangement104 that can be configured with one or more inductive and/or radiantheaters or heating elements disposed adjacent the drum 100, including incontact with the drum 100, which can be longitudinally or axially spacedapart along the drum 100 to heat granules or pellets 42 travelingthrough the drum 100 of the coater 96 to reduce their moisture content.Such a drying arrangement 104 can also include a convective or airdrying arrangement 118 that can be operated instead of and/or inaddition to any induction and/or radiant heating elements to drygranules or pellets 42 in the coater 96.

Such drying air and/or heat can be selectively applied to granules orpellets 42 traveling in the rotating drum 100 of the seasoner coater 96a distance downstream of the inlet 130 of the drum 100 and upstream ofthe outlet 132 of the drum 100. In one preferred seasoner coaterembodiment, granular coating material 43 and/or wetting liquid isapplied to granules or pellets 42 in a coating section 134 of the drum100 disposed adjacent and downstream of the drum inlet 130 before the atleast partially coated granules or pellets 42 reaches a drying section136 of the drum 100 disposed downstream of the coating section 134 andupstream of the drum outlet 132.

FIG. 1B illustrates a second preferred embodiment of a granularabsorbent conveyor and coating system 40 b that is similar to the system40 a shown in FIG. 1A but which introduces coating material downstreamof the pneumatic conveyor conduit inlet 54 by connecting or coupling thecoating material delivery conduit 84 to the pneumatic conveyor conduit52 downstream of the inlet 54. Where the system 40 b also is equippedwith a wetting liquid delivery system 86, the wetting liquid deliveryconduit 94 also is connected to the pneumatic conveyor conduit 52downstream of the inlet or intake 54 of the conduit 52. If desired, thewetting liquid delivery conduit 94 can have one branch 94 a that enableswetting liquid to be introduced into the pneumatic conveyor conduit 52at or adjacent the location where the coating material delivery conduit84 introduces coating material 43 into the pneumatic conveyor conduit 52and/or another branch 94 b that enables wetting liquid to be introducedinto the conduit 52 downstream of the location where the coatingmaterial delivery conduit 84 introduces coating material 43 into thepneumatic conveyor conduit 52.

FIG. 2A illustrates third preferred embodiment of a granular absorbentconveyor and coating system 40 c constructed in accordance with thepresent invention that is similar to FIG. 1A but which has a coatingmaterial manifold 83 from which plurality of pairs of coating materialconduit branches 84 a, 84 b, 84 c, 84 d, 84 e, and 84 f extend that areused to deliver coating material 43 into not only the extrudatedischarge chamber 68 at 85 a but also into the pneumatic conveyorconduit 52 at a plurality of axially or longitudinally spaced apartlocations 85 b, 85 c, 85 d, 85 e, and 85 f downstream of the conduitinlet or intake 54. A manually or selectively operable dispenser, suchas a nozzle, valve or other dispenser that can be electrically and/orelectromagnetically actuated, e.g. solenoid actuated, is disposed ateach location 85 a, 85 b, 85 c, 85 d, 85 e, and 85 f enabling each to beindependently operated to dispense coating material 43 as needed. Whereelectrically and/or electromagnetically actuated, a controller, such asa programmable logic controller (PLC) can be used to selectivelydispense coating material at or through one or more of the dispensers 85a, 85 b, 85 c, 85 d, 85 e, and 85 f, including at or through a pluralityof the dispensers 85 a, 85 b, 85 c, 85 d, 85 e, and 85 f atsubstantially the same time, during operation of system 40 c. FIG. 2Afurther differs from FIG. 1A in that the system 40 c does not employ anywetting liquid delivery system.

FIG. 2B illustrates fourth preferred embodiment of a granular absorbentconveyor and coating system 40 d constructed in accordance with thepresent invention that is similar to FIG. 1B but which has a pluralityof pairs of coating material conduit branches 84 a, 84 b, 84 c, 84 d, 84e, and 84 f used to deliver coating material 43 into the pneumaticconveyor conduit 52 at a plurality of axially or longitudinally spacedapart locations 85 a, 85 b, 85 c, 85 d, 85 e, and 85 f downstream of theconduit inlet or intake 54. A manually or selectively operabledispenser, such as a nozzle, valve or other dispenser that can beelectrically and/or electromagnetically actuated, e.g. solenoidactuated, is disposed at each location 85 a, 85 b, 85 c, 85 d, 85 e, and85 f enabling each to be independently operated to dispense coatingmaterial 43 as needed. Where electrically and/or electromagneticallyactuated, a controller, such as a programmable logic controller (PLC)can be used to selectively dispense coating material at or through oneor more of the dispensers 85 a, 85 b, 85 c, 85 d, 85 e, and 85 f,including at or through a plurality of the dispensers 85 a, 85 b, 85 c,85 d, 85 e, and 85 f at substantially the same time, during operation ofsystem 40 c. FIG. 2B further differs from FIG. 1B in that the system 40d does not employ any wetting liquid delivery system.

FIG. 3A illustrates fifth preferred embodiment of a granular absorbentconveyor and coating system 40 e constructed in accordance with thepresent invention that is similar to FIG. 1A but which has a wettingliquid delivery manifold 93 from which plurality of pairs of wettingliquid conduit branches 94 a, 94 b, 94 c, 94 d, and 94 e extend that areused to deliver wetting liquid into the pneumatic conveyor conduit 52 ata plurality of axially or longitudinally spaced apart locations 95 a, 95b, 95 c, 95 d, and 95 e downstream of the conduit inlet or intake 54. Amanually or selectively operable dispenser, such as a nozzle, valve orother dispenser that can be electrically and/or electromagneticallyactuated, e.g. solenoid actuated, is disposed at each location 95 a, 95b, 95 c, 95 d, and 95 e enabling each to be independently operated todispense wetting liquid as needed during operation of system 40 e. Whereelectrically and/or electromagnetically actuated, a controller, such asa programmable logic controller (PLC) can be used to selectivelydispense wetting liquid at or through one or more of the dispensers 95a, 95 b, 95 c, 95 d, and 95 e, including at or through a plurality ofthe dispensers 95 a, 95 b, 95 c, 95 d, and/or 95 e, including atsubstantially the same time, during operation of system 40 e.

FIG. 3B illustrates sixth preferred embodiment of a granular absorbentconveyor and coating system 40 f constructed in accordance with thepresent invention that is similar to FIG. 1B but which like FIG. 3A hasa wetting liquid delivery manifold 93 from which plurality of pairs ofwetting liquid conduit branches 94 a, 94 b, 94 c, 94 d, and 94 e extendthat are used to deliver wetting liquid from tank 92 into the pneumaticconveyor conduit 52 at a plurality of axially or longitudinally spacedapart locations 95 a, 95 b, 95 c, 95 d, and 95 e along the conduit 52located downstream of the conduit inlet or intake 54. A manually orselectively operable dispenser, such as a nozzle, valve or otherdispenser that can be electrically and/or electromagnetically actuated,e.g. solenoid actuated, is disposed at each location 95 a, 95 b, 95 c,95 d, and 95 e enabling each to be independently operated to dispensewetting liquid as needed during operation of system 40 f. Whereelectrically and/or electromagnetically actuated, a controller, such asa programmable logic controller (PLC) can be used to selectivelydispense wetting liquid at or through one or more of the dispensers 95a, 95 b, 95 c, 95 d, and 95 e, including at or through a plurality ofthe dispensers 95 a, 95 b, 95 c, 95 d, and/or 95 e, including atsubstantially the same time, during operation of system 40 f.

FIG. 4A illustrates a seventh preferred embodiment of a granularabsorbent conveyor and coating system 40 g constructed in accordancewith the present invention that is similar to FIG. 1A but which has acoating material manifold 83 from which plurality of pairs of coatingmaterial conduit branches 84 a, 84 b, 84 c, 84 d, 84 e, and 84 f extendthat are used to deliver coating material 43 not only into the extrudatedischarge chamber 68 at 85 a but also into the pneumatic conveyorconduit 52 at a plurality of axially or longitudinally spaced apartlocations 85 b, 85 c, 85 d, 85 e, and 85 f along the conduit 52 locateddownstream of the conduit inlet or intake 54. A manually or selectivelyoperable dispenser, such as a nozzle, valve or other dispenser that canbe electrically and/or electromagnetically actuated, e.g. solenoidactuated, is disposed at each location 85 a, 85 b, 85 c, 85 d, 85 e, and85 f enabling each to be independently operated to dispense coatingmaterial 43 as needed. Where electrically and/or electromagneticallyactuated, a controller, such as a programmable logic controller (PLC)can be used to selectively dispense coating material at or through oneor more of the dispensers 85 a, 85 b, 85 c, 85 d, 85 e, and 85 f,including at or through a plurality of the dispensers 85 a, 85 b, 85 c,85 d, 85 e, and 85 f at substantially the same time, during operation ofsystem 40 g.

The system 40 g of FIG. 4A also has a wetting liquid delivery manifold93 from which plurality of pairs of wetting liquid conduit branches 94a, 94 b, 94 c, 94 d, and 94 e extend that are used to deliver wettingliquid into the pneumatic conveyor conduit 52 at a plurality of axiallyor longitudinally spaced apart locations 95 a, 95 b, 95 c, 95 d, and 95e along the conduit 52 downstream of the conduit inlet or intake 54. Amanually or selectively operable dispenser, such as a nozzle, valve orother dispenser that can be electrically and/or electromagneticallyactuated, e.g. solenoid actuated, is disposed at each location 95 a, 95b, 95 c, 95 d, and 95 e enabling each to be independently operated todispense wetting liquid as needed during operation of system 40 g. Whereelectrically and/or electromagnetically actuated, a controller, such asa programmable logic controller (PLC) can be used to selectivelydispense wetting liquid at or through one or more of the dispensers 95a, 95 b, 95 c, 95 d, and 95 e, including at or through a plurality ofthe dispensers 95 a, 95 b, 95 c, 95 d, and/or 95 e, including atsubstantially the same time, during operation of system 40 g.

FIG. 4B illustrates an eighth preferred embodiment of a granularabsorbent conveyor and coating system 40 h constructed in accordancewith the present invention that is similar to FIG. 1B but which has acoating material manifold 83 from which plurality of pairs of coatingmaterial conduit branches 84 a, 84 b, 84 c, 84 d, 84 e, and 84 f extendthat are used to deliver coating material 43 into the pneumatic conveyorconduit 52 at a plurality of axially or longitudinally spaced apartlocations 85 b, 85 c, 85 d, 85 e, and 85 f along the conduit 52downstream of the conduit inlet or intake 54. A manually or selectivelyoperable dispenser, such as a nozzle, valve or other dispenser that canbe electrically and/or electromagnetically actuated, e.g. solenoidactuated, is disposed at each location 85 a, 85 b, 85 c, 85 d, 85 e, and85 f enabling each to be independently operated to dispense coatingmaterial 43 as needed. Where electrically and/or electromagneticallyactuated, a controller, such as a programmable logic controller (PLC)can be used to selectively dispense coating material at or through oneor more of the dispensers 85 a, 85 b, 85 c, 85 d, 85 e, and 85 f,including at or through a plurality of the dispensers 85 a, 85 b, 85 c,85 d, 85 e, and 85 f at substantially the same time, during operation ofsystem 40 h.

The system 40 h of FIG. 4B also has a wetting liquid delivery manifold93 from which plurality of pairs of wetting liquid conduit branches 94a, 94 b, 94 c, 94 d, and 94 e extend that are used to deliver wettingliquid into the pneumatic conveyor conduit 52 at a plurality of axiallyor longitudinally spaced apart locations 95 a, 95 b, 95 c, 95 d, and 95e along the conduit 52 downstream of the conduit inlet or intake 54. Amanually or selectively operable dispenser, such as a nozzle, valve orother dispenser that can be electrically and/or electromagneticallyactuated, e.g. solenoid actuated, is disposed at each location 95 a, 95b, 95 c, 95 d, and 95 e enabling each to be independently operated todispense wetting liquid as needed during operation of system 40 h. Whereelectrically and/or electromagnetically actuated, a controller, such asa programmable logic controller (PLC) can be used to selectivelydispense wetting liquid at or through one or more of the dispensers 95a, 95 b, 95 c, 95 d, and 95 e, including at or through a plurality ofthe dispensers 95 a, 95 b, 95 c, 95 d, and/or 95 e, including atsubstantially the same time, during operation of system 40 h.

FIG. 5A illustrates an elongate section 150 a of the conduit 52 of apneumatic conveyor 44 that is used to convey or transport absorbentgranules or pellets 42 extruded from the extruder 48 to a location 50remote from the extruder 48 that can be a handling and/or processingstation 60 such as a station where packaging of the absorbent granulesor pellets 42 can be done, a station where the absorbent granules orpellets 42 can be coated, such as the coater station 96 like thatdepicted in FIG. 1A, and/or a station where a treatment, such as aliquid treatment, can be applied to the absorbent granules or pellets42. The elongate section 150 a of the pneumatic conveyor conduit 52 canbe made of a tubular duct 152 a that can be formed of a flexiblematerial, such as plastic, foil, metal, or the like, of circular, squareand/or generally rectangular cross-section through which gas, preferablyair, flows carrying at least a plurality of pairs of the absorbentgranules or pellets 42 toward the outlet or discharge 58 of the conduit52.

Such a duct 152 a has a width or diameter of at least two inches withthe width or diameter of the duct 152 a ranging from two inches totwelve inches with a preferred duct 152 a having a width or diameterranging between four inches and nine inches enabling a volumetric flowrate of air to be transported through the duct 152 a of at least 500cubic feet per minute, preferably between 1000 CFM and 2000 CFM, andmore preferably between 1300 CFM and 1700 CFM. This produces a pneumaticconveyor 44 having an elongate conduit 52 that is an elongate duct 152 athrough which a sufficient flow or flow rate of air passes that producesa turbulent flow regime of air flowing within the duct 152 a.Turbulently flowing air flowing in the conduit 52, i.e., through theduct 152 a, causes the plurality of pairs of absorbent granules orpellets 42 to come into contact with one another as well as with aninner surface 154 a of an endless sidewall 156 a that forms the duct 152a. This contact can be and preferably is abrasive in nature causing atleast some of the outer surface of each one of a plurality of pairs ofgranules or pellets 42 entrained in the turbulently flowing air to beabraded or polished in a surface preparation step, e.g. polishing step,which is carried out while the granules or pellets 42 are beingtransported.

Surface preparing, e.g. lightly abrading, of the granules or pellets 42in the pneumatic conveyor conduit 52, e.g., duct 150 a, by the pneumaticconveyor 44 during conveyance of the granules or pellets 42 toward theconduit outlet or discharge 58 can be carried out whether the granulesor pellets 42 are ever coated and/or ever otherwise treated after beingextruded from the extruder 48. If desired, as discussed in more detailbelow with regard to FIGS. 5A and 5B, surface preparation of uncoatedgranules or pellets 42 can be carried out during transport in theconduit 52 by the pneumatic conveyor 44 in such a surface preparationstep in preparation for coating the surface prepared but uncoatedgranules or pellets 42 in a subsequent coating step or operationperformed at a station following transport by the pneumatic conveyor 44.If desired, as discussed in more detail below with regard to FIGS. 6Aand 6B, surface preparation of absorbent granules or pellets 42 can becarried out during transport in the conduit 52 by the pneumatic conveyor44 in a surface preparation step that can be carried out with a coatingstep also performed during transport with the steps being performedseparately from one another and/or at substantially the same time.

Such a surface preparation step removes projections 160 and surfaceirregularities 162 from granules or pellets 42 being transported by thepneumatic conveyor 44 advantageously breaking off at least a pluralityof pairs of projections 160 and/or surface irregularities 162 from thegranules or pellets 42 being transported in the duct 152 a producing atleast a plurality of pairs of fines 164 from abrasive surfacepreparation that are smaller in size than an average size of thegranules or pellets 42 transported in the duct 152 a during pneumaticconveyor operation. In one preferred surface preparation step andimplementation, at least a plurality of the plurality of pairs of fines164 produced during polishing have a size no greater than one-tenth theaverage size of the granules or pellets 42 transported in the duct 152 aduring pneumatic conveyor operation. In another preferred surfacepreparation step and implementation, each one of the plurality of pairsof fines 164 produced during polishing have a size no greater thanone-tenth the average size of the granules or pellets 42 transported inthe duct 152 a during pneumatic conveyor operation.

The smaller sized fines 164 of granular absorbent produced duringpneumatic conveyor operation during the surface preparation step arepackaged with the absorbent granules or pellets 42 making up at leasttwo percent and preferably at least five percent by packaged granularabsorbent weight. The inclusion of such smaller sized fines 164 made ofthe same absorbent material as the absorbent granules or pellets 42 inretail or commercial packages of the granular absorbent advantageouslypromotes generally horizontal clumping of at least a plurality of pairsof granules or pellets 42 during use as an absorbent. In one preferredimplementation and embodiment, the inclusion of at least two percent ofthe fines 164 produced during transport of absorbent granules or pellets42 in conduit 52, e.g., elongate duct 152 a, during pneumatic conveyoroperation in retail packaged or commercially packaged granular pet oranimal litter formed of such granules or pellets 42 and fines 164produces a self-clumping lightweight pet or animal litter having adensity of less than about 35 pounds and preferably less than 28 poundsthat produces a clump formed of litter composed of a plurality of pairsof granules or pellets 42 and fines 164 by discharged pet or animalurine having a generally horizontal extent that is greater than avertical extent. In short, such a pet or animal litter formulationformed of coated or uncoated absorbent granules or pellets 42 mixedtogether with at least five percent fines 164 by total packaged animalor pet litter weight produces a clump when wetted by animal or pet urinethat is longer than the clump is deep having a lengthwise extent of theclump extending generally horizontally in the rest of the unused orunspent litter disposed in a litter box or the like holding the animalor pet litter. Such a clump also advantageously forms on top of otherpellets 42 and fines 164 enabling the clump to be easily scooped up.

Surface preparation the absorbent granules or pellets 42 in such asurface preparation or polishing step while the granules or pellets 42are being transported by turbulently flowing air flowing through theconduit 52, e.g., through duct 152 a, of the pneumatic conveyor 44 alsoadvantageously smoothes and/or polishes the outer surface of at least aplurality of pairs of the granules or pellets 42 during surfacepreparation and transport. In one preferred implementation andembodiment for carrying out the surface preparation step, each one ofthe granules or pellets 42 transported by the pneumatic conveyor 42 inthe conduit 52 is at least partially smoothed or polished by the surfacepreparation step such that at least a portion, preferably substantiallyall, of the outer surface of each granule or pellet 42 is smoothedand/or polished during pneumatic conveyor transport.

Smoothing and/or polishing of the outer surface of the granules orpellets 42 during pneumatic conveyor transport advantageously enables acoating to be applied to each one of at least a plurality of pairs ofthe granules or pellets 42 that is thinner and more uniform than if thesurface preparation step was not carried out on the granules or pellets42 during pneumatic conveyor transport. Where the granules or pellets 42are coated, such as with a granular coating material 43 in accordancewith any formulation specified above, the outer layer or coatingsubstantially completely encapsulating the outer surface of each coatedgranule or pellet 42 has a substantially uniform coating or layerthickness that does not deviate in thickness by more than 35%. Inanother implementation and embodiment, executing the surface preparationstep during pneumatic conveyor transport produces an outer coatinghaving a substantially uniform thickness having less than 10% deviationin coating thickness throughout the layer or coating.

With continued reference to FIG. 5A, the duct 162 a from which thepneumatic conveyor conduit 52 is formed has an endless sidewall 156 athat can be ribbed having at least one rib forming at least a pluralityof pairs of rib projections 166 a extending inwardly from the inner ductsurface 154 a against which granules or pellets 42 can contact, e.g.,impact, during transport of the granules or pellets 42 in airturbulently flowing through the duct 152 a. Such rib projections 166 acan be formed by a plurality of pairs of ribs longitudinally or axiallyuniformly spaced apart substantially the length of the conduit 52, e.g.,duct, or can be formed by a spiral or helical wire that supports theduct sidewall that extends substantially the entire length of theconduit 52, e.g., duct. As is shown in FIG. 5A, the shape of the ribprojections 166 a of the duct 152 a can be wavy or sinusoidal. The shapeof the rib projections 166 b of the duct 152 b can also have a zig-zagshape if desired, such as is depicted by the section of pneumaticconveyor conduit 52 b shown in FIG. 5B.

FIGS. 6A and 6B depict sections of duct 156 a and/or 156 b, e.g.,flexible duct, that form a pneumatic conveyor conduit 52 used in agranular absorbent conveyor and coating system constructed in accordancewith the present invention, e.g. system(s) 40 a-40 h, to polish granulesor pellets 42, including relatively thin plate, disc, disk, cupped,concave and especially flake-shaped granules or pellets 42, in apolishing step that produces fines 164 as uncoated granules or pellets42 are transported in a transport step through the conduit 52, e.g.,duct, from the extruder 48 towards the conduit outlet or discharge 58.The polishing step can be executed independently or separately fromcoating the granules or pellets 42 with coating material 43, e.g.granular (powdered) coating material 43, in a coating step that is alsocarried out while the granules or pellets 42 are being transported byair turbulently flowing through the conduit 52 a or 52 b toward theconduit outlet or discharge 58. Where the polishing step is carried outas a step separate from the coating step, the polishing step preferablyis performed in a section of the conduit 52 a or 52 b disposed upstreamof another section of the conduit 52 a or 52 b where the coating step isperformed. In another implementation and embodiment, the polishing stepand coating step can be performed substantially simultaneously includingperforming the polishing step and coating step along substantially theentire length of the conduit 52 a and/or 52 b such that the polishingstep and coating step can be substantially performed during the entiretransport step.

In a preferred surface treatment or preparation step, thepellet-abrading interior surface of the granule or pellet transportconduit 52 of the pneumatic conveyor produces fines 164 by breakingpieces off of the granular absorbent granules or pellets 42 beingtransported through the pneumatic conveyor conduit 52 that are smallerin size than each one of the granules or pellets 42 being transported.In one preferred surface treatment or preparation step, uncoatedgranules or pellets 42 are used such that the fines 164 produced aregranular absorbent fines formed by the ribbed, roughened and/or threedimensionally contoured pellet-abrading interior surface of thepneumatic conveyor conduit 52 breaking pieces of granular absorbent offof uncoated granules or pellets 42 as the granules or pellets 42 arebeing transported through the conduit 52.

In one preferred surface treatment or preparation step, the amount ofgranular absorbent fines 164 produced by the time the granules orpellets 42 exit the conduit 52 constitutes at least 2% by weight of thetotal granular absorbent material exiting the conduit 52 where the totalgranular absorbent material exiting the conduit is defined as being thetotal amount of granular absorbent fines 164 plus the total amount ofthe granules or pellets 42 of granular absorbent material. In anotherpreferred surface treatment or preparation step, the amount of granularabsorbent fines 164 produced by the time the granules or pellets 42 exitthe conduit constitutes at least 5% by weight of the total granularabsorbent material exiting the conduit 52. In still another preferredsurface treatment or preparation step, the amount of granular absorbentfines 164 produced by the time the granules or pellets 42 exit theconduit constitutes at least 10% by weight of the total granularabsorbent material exiting the conduit 52. In a further preferredsurface treatment or preparation step, the amount of granular absorbentfines 164 produced by the time the granules or pellets 42 exit theconduit constitutes at least 15% by weight of the total granularabsorbent material exiting the conduit 52.

In one preferred surface treatment or preparation step, thepellet-abrading interior surface of the conduit 52 produces fines 164that are less than one half of the size of the granules or pellets 42exiting the conduit 52. In one such preferred surface treatment orpreparation step, the pellet-abrading interior surface of the conduit 52produces fines 164 that each have a size less than one half of the sizeof the granules or pellets 42 exiting the conduit 52. In anotherpreferred surface treatment or preparation step, the pellet-abradinginterior surface of the conduit 52 produces fines 164 that are less thanone quarter of the size of the granules or pellets 42 exiting theconduit 52. In one such preferred surface treatment or preparation step,the pellet-abrading interior surface of the conduit 52 produces fines164 with at least 25% of the fines 164 produced having a size less thanone quarter of the size of the granules or pellets 42 exiting theconduit 52. In another such preferred surface treatment or preparationstep, the pellet-abrading interior surface of the conduit 52 producesfines 164 with at least 25% of the fines 164 produced having a size lessthan one half of the size of the granules or pellets 42 exiting theconduit 52 and at least 15% of the fines 164 having a size less than onequarter of the size of the granules or pellets 42 exiting the conduit52.

Producing a granular absorbent having such a mixture of granularabsorbent granules or pellets 42 and smaller granular absorbent fines164 forms clumps having at least a plurality of pairs, i.e., at leastthree granules or pellets 42, when granules or pellets 42 and fines 164are wetted, e.g. with water, urine and/or liquid fecal matter, whichdesirably form or clump in a generally horizontal orientation in a boxof granular absorbent, e.g., litter box filled with fines containinggranular absorbent. Producing such a granular absorbent having such amixture of granular absorbent granules or pellets 42 and smallergranular absorbent fines 164 produces clumps in a generally horizontaldirection or orientation that each are formed of at least a plurality ofpairs, i.e., at least three granules or pellets 42, when granules orpellets 42 and fines 164 are wetted, e.g. with water, urine and/orliquid fecal matter, which more desirably form or clump on top of a boxof granular absorbent, e.g., on top of a litter box filled with finescontaining granular absorbent containing both fines 164 and granules orpellets 42.

Where the granules or pellets 42 of granular absorbent are extruded froma starch-containing admixture at a minimum extruder pressure and minimumextruder temperature that produces extruded granules or pellets 42 eachhaving at least 10% water-soluble binder, and preferably at least 15%water-soluble binder, by uncoated pellet weight formed from starch inthe admixture during extrusion, without the use or presence of any otherbinder additive, a preferred method of coating during extruded granuleor pellet transport in a pneumatic conveyor conduit 52 uses a tackyouter granule or pellet surface formed of wetted water-soluble binder asan outer layer of glue on the outer surface of each granule or pellet 42to which coating material 43 sticks to or adheres during transportthrough the conduit 52. In one preferred coating method, granules orpellets 42 are drawn from the discharge chamber 68 of the extruder 48into the pneumatic conveyor conduit 52 while water-soluble binder in theouter surface of the uncoated granules or pellets 42 is still tacky,e.g. sticky, from extrusion as the granules or pellets 42 can still bemoist enough after extrusion for the water-soluble binder in the outersurface of each uncoated granule or pellet 42 to still be tacky orsticky. Coating material 43 entrained in the air carrying the granulesor pellets 42 through the conduit 52 adheres or sticks to the tackybinder on the outer surface of each granule or pellet 42 with the binderat least partially coating or encapsulating particles or granules of theadhered coating material 43. In addition to the air flowing through theconduit 52 drying each granule or pellet 42 as each granule or pellet 42is at least being partially coated with coating material 43 glued to thegranule or pellet 42 with water-soluble binder from the granule orpellet itself, the coating material 43 also dries at least the outersurface of each granule or pellet 42 it becomes adhered to during pelletcoating. As a result, the very act of coating each granule or pellet 42with the drier coating material 43 not only dries each granule or pellet42 during coating with the coating material 43, this drying action frombeing coated with coating material 43 dries and cures the tackywater-soluble binder of each granule or pellet 42 that is on the outersurface of each granule or pellet 42 bonding the coating material 43thereto.

Where the granules or pellets 42 of granular absorbent are extruded froma starch-containing admixture at a minimum extruder pressure and minimumextruder temperature that produces extruded granules or pellets 42 eachhaving at least 10% water-soluble binder, and preferably at least 15%water-soluble binder, by uncoated pellet weight formed from starch inthe admixture during extrusion, without the use or presence of any otherbinder additive, another preferred method of coating during extrudedgranule or pellet transport in a pneumatic conveyor conduit 52 includesa wetting step where each granule or pellet 42 is wetted with a wettingliquid, such as disclosed above, which preferably includes water thatmakes at least some of the water-soluble binder in the outer surface ofeach granule or pellet 42 sticky or tacky by at least dissolving orsolubilize and some of the water-soluble binder in the outer granule orpellet surface. This wetting step can be performed before coatingmaterial 43 is introduced into the air flowing through the conduit 42that is carrying the granules or pellets 42 a way from the extruder 48and can also be performed while the granules or pellets 42 and coatingmaterial 43 are flowing together through the conduit 52. Once eachgranule or pellet 42 is sufficiently wetted with the wetting liquid tomake at least a portion of the outer surface of each granule or pellet42 sufficiently tacky or sticky for coating material 43 to adherethereto, coating of each granule or pellet 42 with coating material 43advantageously dries each granule or pellet 42 and preferably also curesand hardens the binder on the outer surface of each granule or pellet 42substantially permanently fixing the coating material 43 theretoproducing an outer layer or coating at least partially coating eachcoated granule or pellet 42 formed of a relatively hard matrix of thecured hardened binder and particles or granules of coating material 43.

The particles or granules of coating material 43 are drier than thegranular absorbent granules or pellets 42 having a moisture content lessthan the moisture content of the granules or pellets 42 upon enteringthe pneumatic conveyor conduit 52. The particles or granules of coatingmaterial 43 are smaller than the granular absorbent granules or pellets42 and preferably much smaller with the particles or granules of coatingmaterial 43 preferably being no larger than 1/10^(th) the size of thegranular absorbent granules or particles 42. In a preferred coatingmaterial, each granule or particle of coating material 43 has a size nogreater than 1/50^(th) the size of the granular absorbent granules orparticles 42.

In a preferred coating step, at least partially coating the granules orpellets 42 with drier coating material 43, which preferably includesparticles or granules of bentonite, e.g., powdered bentonite, reducesthe moisture content of the granules or pellets 42 by at least 1% bypellet weight from the moisture content of the granules or pellets 42entering the conduit 52. In another preferred coating step, a dryingstep preferably is performed during coating where at least partiallycoating the granules or pellets 42 with such coating material 43 driesthe granules or pellets 42 by reducing the moisture content of thegranules or pellets 42 by at least 2% by application of the coatingmaterial 43 while the granules or pellets 42 are being transportedthrough the conduit 52. In another such coating step where drying alsois performed, the moisture content of the granules or pellets is reducedby at least 3%. In still another such coating step where drying also isperformed, the moisture content of the granules or pellets is reduced byat least 4%. In a further such coating step where drying also isperformed, the moisture content of the granules or pellets is reduced byat least 5%. In each of these preferred coating steps where dryingoccurs, application of the coating material 43 preferably causes theaforementioned reduction in moisture content with the air flowingthrough the conduit 52 reducing the moisture content of each granule orpellet 42 exiting the conduit 52 by at least an additional 1% by pelletweight.

Such a coating step and method of granule or pellet coating where eachgranule or pellet 42 has water-soluble binder sufficient to provide asticky or tacky outer granule or pellet surface when wettedadvantageously provides a coating method of the present invention wherethe granule or pellet itself provides the source of the glue, adhesiveor binder to which the coating material 43 adheres or sticks to when atleast partially coating each granule or pellet 42 during granule orpellet transport in a pneumatic conveyor conduit 52 away from theextruder 48. Such a coating step and method of granule or pellet coatingalso advantageously helps dry each granule or pellet 42 during coatingduring granule or pellet transport through the pneumatic conveyorconduit 52 while each granule or pellet 42 is being coated with coatingmaterial 43 during granule or pellet transport through the pneumaticconveyor conduit 52.

Where the granular absorbent is to be coated, a coating material thatpreferably is a granular coating material comprised of bentonite isintroduced during transport of the granular absorbent to at leastpartially coat the granular absorbent during transport. Granular coatingmaterial can be applied onto freshly extruded granular absorbent uponextrusion while tacky to better adhere the coating material while alsodrying the granular absorbent during coating of the granular absorbenthelping to minimize shrinkage and density. Coating material can befurther applied to the granular absorbent while it is being transportedat one or more locations downstream of the extruder to further coat thegranular absorbent.

A wetting liquid can be applied to granular absorbent to treat granularabsorbent while the granular absorbent is being transported. In apreferred method, wetting liquid is applied in a wetting step duringgranular absorbent transport where a coating step is performed to wet atleast partially coated granular absorbent tackifying it to enable it toaccept additional coating material to further coat it.

If desired, coating material can be applied to granular absorbent duringtransport of the granular absorbent at a plurality of locationsdownstream of the extruder. Where wetting liquid is used to facilitategranular absorbent coating, wetting liquid can also be applied togranular absorbent during transport of the granular absorbent at aplurality of locations downstream of the extruder.

In one system and method, coating material is repeatedly applied togranular absorbent during the coating step to granular absorbent beingtransported at a plurality of locations downstream of the extruder andwetting liquid is repeatedly applied to granular absorbent to wet thegranular absorbent tackifying it so additional coating material willadhere to the tacky granular absorbent. Such application of coatingmateriel and wetting liquid can be done sequentially with coatingmaterial applied first before applying wetting liquid, can be donesubstantially simultaneously, and/or can be done as needed in at leastpartially coating granular absorbent during transport away from anextruder.

Understandably, the present invention has been described above in termsof one or more preferred embodiments and methods. It is recognized thatvarious alternatives and modifications may be made to these embodimentsand methods that are within the scope of the present invention. Variousalternatives are contemplated as being within the scope of the presentinvention. It is also to be understood that, although the foregoingdescription and drawings describe and illustrate in detail one or morepreferred embodiments of the present invention, to those skilled in theart to which the present invention relates, the present disclosure willsuggest many modifications and constructions, as well as widelydiffering embodiments and applications without thereby departing fromthe spirit and scope of the invention.

What is claimed is:
 1. A system for producing granular absorbentcomprising: (a) an extruder that extrudes a plurality of pairs ofabsorbent pellets per second; and (b) a pneumatic conveyor comprised ofan elongate conduit having an intake that receives and transports theextruded pellets through the conduit using air flowing through theconduit from an intake of the conduit to a discharge of the conduit; andwherein the extruded pellets are processed or treated while beingtransported through the pneumatic conveyor conduit.
 2. The system ofclaim 1 wherein the extruded pellets are dried while being transportedby air flowing through the conduit.
 3. The system of claim 2 wherein theextruded pellets are dried reducing their moisture content by at least2% while being transported by air flowing through the conduit.
 4. Thesystem of claim 2 wherein the extruded pellets are dried reducing theirmoisture content by at least 3% while being transported by air flowingthrough the conduit.
 5. The system of claim 1 further comprising amaterial delivery system that introduces material carried with thepellets transported in the conduit that dries the pellets as the pelletsare being transported through the conduit by reducing the moisturecontent of the pellets exiting the conduit to a moisture content that isat least 1% less than the moisture content of the pellets entering theconduit.
 6. The system of claim 5 wherein the material that dries thepellets during transport through the conduit is comprised of bentonite.7. The system of claim 6 wherein the material that dries the pelletsduring transport through the conduit is comprised of powdered bentonitehaving a moisture content less than the moisture content of the pelletsentering the conduit.
 8. The system of claim 7 wherein the powderedbentonite at least partially coats each pellet with bentonite duringtransport of the pellets through the conduit.
 9. The system of claim 8wherein the powdered bentonite dries the pellets during transport of thepellets through the conduit to a moisture content when the pellets exitthe conduit that is at least 2% less than the moisture content of thepellets entering the conduit.
 10. The system of claim 5 wherein thematerial is introduced into the conduit after the pellets have enteredthe conduit.
 11. The system of claim 5 wherein the extruder has anextrudate discharge chamber in fluid flow communication with the intakeof the conduit and wherein the material is introduced into the extrudatedischarge chamber such that the material and extruded pelletssubstantially simultaneously enter the intake of the conduit.
 12. Thesystem of claim 1 further comprising a coating material delivery systemthat introduces coating material that at least partially coats thepellets while the pellets are being transported in the duct.
 13. Thesystem of claim 12 wherein the coating material is comprised ofbentonite and wherein the pellets are at least partially coated withbentonite while the pellets are transported through the duct.
 14. Thesystem of claim 13 wherein the coating material is comprised of powderedor granular bentonite having a moisture content less than the moisturecontent of the pellets when entering the conduit and wherein the pelletsare dried during coating of the pellets with the powdered or granularbentonite.
 15. The system of claim 14 wherein the coating material driesthe pellets during coating of the pellets with the coating materialduring transport of the pellets through the conduit by reducing themoisture content of the pellets by at least 1%.
 16. The system of claim14 wherein the coating material dries the pellets during coating of thepellets with the coating material during transport of the pelletsthrough the conduit by reducing the moisture content of the pellets byat least 2%.
 17. The system of claim 12 wherein the extruder has anextrudate discharge chamber in fluid flow communication with the intakeof the conduit and wherein the coating material delivery system is influid flow communication with the extrudate discharge chamberintroducing the coating material into the extrudate discharge chambersuch that the coating material and extruded pellets enter the intake ofthe conduit from the extrudate discharge chamber.
 18. The system ofclaim 12 wherein coating material delivery system is in fluid flowcommunication with the conduit downstream of the extruder introducingcoating material into the conduit at or downstream of the intake of theconduit.
 19. The system of claim 12 wherein the coating materialdelivery system introduces the coating material while the pellets have atacky outer surface from the pellets being extruded by the extruderwhereby coating material adheres to the tacky outer surface of thepellets during transport of the pellets through the conduit.
 20. Thesystem of claim 19 wherein coating material adhering to the tacky outersurface of pellets being transported through the conduit dries the outersurface of the pellets bonding the coating material to the outer surfaceof the pellets.
 21. The system of claim 20 wherein the tacky outersurface of the pellets being transported through the conduit iscomprised of water soluble binder and wherein adhering of the coatingmaterial to the tacky outer surface of the pellets causes the watersoluble binder to bond the coating material thereto.
 22. The system ofclaim 21 wherein adhering of the coating material to the tacky outersurface of the pellets dries and hardens the water soluble binderbonding the coating material thereto.
 23. The system of claim 19 whereinthe extruder has an extrudate discharge chamber in fluid flowcommunication with the intake of the conduit and wherein the coatingmaterial delivery system is in fluid flow communication with theextrudate discharge chamber introducing the coating material into theextrudate discharge chamber such that the coating material and extrudedpellets enter the intake of the conduit from the extrudate dischargechamber.
 24. The system of claim 19 wherein coating material deliverysystem is in fluid flow communication with the conduit downstream of theextruder introducing coating material into the conduit at or downstreamof the intake of the conduit.
 25. The system of claim 1 furthercomprising a liquid delivery system that introduces liquid carried withthe pellets transported in the conduit that treats the pellets as thepellets are being transported through the conduit.
 26. The system ofclaim 1 wherein the conduit is comprised of a pellet abrading innersurface that abrades the pellets as the pellets are transported throughthe conduit producing at least a plurality of pairs of fines smaller insize than the size of the pellets that exit the conduit.
 27. The systemof claim 26 wherein at least 2% fines are produced by total granularabsorbent weight when the pellets and fines exit the conduit.
 28. Thesystem of claim 1 wherein the conduit is comprised of a pellet abradinginner surface that abrades the pellets as the pellets are transportedthrough the conduit producing at least a plurality of pairs of finessmaller in size than the size of the pellets that exit the conduitproducing a granular absorbent mixture comprised of the pellets andfines that form clumps of pellets and fines that extend generallyhorizontally when pellets and fines are wetted with water.
 29. Thesystem of claim 1 wherein the conduit is comprised of a pellet abradinginner surface that abrades the pellets as the pellets are transportedthrough the conduit producing at least a plurality of pairs of finessmaller in size than the size of the pellets that exit the conduitproducing a granular absorbent mixture comprised of the pellets andfines that form a clump of pellets and fines wetted with water thatextends generally horizontally and on top of other pellets.